Night Vision Tube Nomenclature: Grades & Designations
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QDEF TECHNICAL // IMAGE INTENSIFIERS
Night Vision Tube Nomenclature Explained
24UA. 20UM. XLSH. SLH. PH. M24H. ECHO. 4G. NVT-5. 10160. 11769. Night vision tube nomenclature can look like alphabet soup until you understand what each designation is actually telling you.
Some designations describe physical tube format. Some describe a manufacturer qualification level. Others identify performance minimums, spot specifications, phosphor, gain-control architecture, or technology family.
And one of the most important things to understand is that the grade printed on a tube does not tell you the exact performance of that individual intensifier.
THE FIRST RULE //
Minimum Specification Is a Floor — Not a Ceiling.
When a tube is classified into a particular specification or qualification family, that designation establishes requirements the tube met for that classification. It does not mean the tube will measure exactly at those minimums.
Individual tubes can—and frequently do—exceed their required minimum performance. Sometimes they exceed it substantially.
A nominally lower-grade tube can outperform an individual tube carrying a higher-grade designation. For example, an unusually strong Elbit XLSH can have better measured specifications, cleaner cosmetics, or both than an individual tube from a nominally higher qualification family.
Compare the individual tube—not just the letters printed on it.
What Does a Tube Designation Actually Tell You?
There is no single universal nomenclature system shared by L3Harris, Twenty-Six Defense (formerly Elbit Systems of America), Photonis/Exosens, and NNVT. Each manufacturer has its own product families and qualification structure.
That means a number in one manufacturer's designation should not automatically be compared with a similar-looking number from another manufacturer.
10160 / 11769
Describes tube architecture and, traditionally, the method used to interface with gain control.
18 / 20 / 22 / 24
Common L3Harris performance-series designations associated with qualification minimums.
XLSH / SLH / PH / M-Series
Twenty-Six Defense / legacy Elbit commercial and specification-family nomenclature encountered throughout the night vision market.
ECHO / 4G / NVT
Manufacturer-specific technology or product families that should not be treated as direct equivalents to L3Harris or Twenty-Six Defense / legacy Elbit grades.
HOW DO THESE LABELS RELATE TO ACTUAL PERFORMANCE? OPEN THE IMAGE INTENSIFIER TUBE GUIDE →
Understanding L3Harris Tube Designations
L3Harris is best known in the commercial night vision market for its high-performance unfilmed Gen III image intensifiers.
A designation such as 20UM or 24UA contains two useful pieces of information: the number identifies the performance series, while the letters identify the applicable qualification / spot-spec family.
| Series | Common Examples | Commonly Published Minimum FOM | What It Tells You |
|---|---|---|---|
| 18 Series | 18UM / 18UA | Approx. 1540 class | Lower qualification floor within the commonly encountered L3 commercial unfilmed families. Individual performance may be considerably higher. |
| 20 Series | 20UM / 20UA | Approx. 1792 class | A widely encountered high-performance unfilmed qualification family. Individual tubes routinely vary above their minimums. |
| 22 Series | 22UM / 22UA | Approx. 1920 class | Higher qualification threshold than 20-series, but still not a statement of the exact measured FOM of every 22-series tube. |
| 24 Series | 24UM / 24UA | Approx. 2160 class | One of the higher commonly encountered L3 commercial qualification families used in premium systems. |
Qualification requirements can vary by contract, production program, configuration, and manufacturer documentation. Always use the actual tube data record when evaluating an individual intensifier.
A 24-series tube has a higher qualification floor than a 20-series tube. That does not mean every individual 24 will outperform every individual 20 in every metric.
A strong 20-series tube may exceed its minimum by a wide margin and overlap higher qualification families in individual measured specifications.
UA vs UM
The suffix is another area where buyers frequently assume too much. A UA designation should not simply be interpreted as “better-performing” than UM.
The distinction is heavily associated with the qualification and allowable cosmetic / spot criteria applied to the tube.
Military Qualification
UM is commonly associated with military-style qualification and spot-spec requirements.
A UM tube can still have extremely high measured SNR, FOM, excellent EBI and halo, and an exceptionally clean image.
Aviation Qualification
UA is associated with stricter aviation-oriented cosmetic / spot acceptance requirements.
It is particularly attractive when image cleanliness and central-zone cosmetics are a high priority.
Both are 24-series tubes. UA does not automatically mean higher SNR, higher gain, lower EBI, or higher measured FOM than UM.
The suffix tells you something about qualification. The individual data tells you how that specific tube actually performs.
Understanding Twenty-Six Defense / Elbit Tube Designations
Elbit Systems of America is now Twenty-Six Defense. As the 2026 branding transition moves through the night vision market, many existing image intensifier tubes, data sheets, product listings, and night vision systems will continue to carry the Elbit name.
For buyers researching Elbit night vision tubes, designations such as XLSH, SLH, PH, YH, VH, M16H, M18H, M20H, M22H, and M24H remain important. The manufacturer branding is changing, but these legacy Elbit designations remain relevant when identifying, comparing, and servicing existing image intensifiers.
ELBIT SYSTEMS OF AMERICA IS NOW TWENTY-SIX DEFENSE — READ THE INDUSTRY UPDATE →
Looking for Elbit tubes? Quad Defense is transitioning applicable product terminology from Elbit Systems of America to Twenty-Six Defense as the new branding rolls out.
During this transition, you may see both names used throughout the night vision market. Quad Defense will continue referencing Elbit where necessary to identify legacy tube designations, documentation, and products customers already know under that name.
| Designation | General Family | How to Interpret It |
|---|---|---|
| XLSH | Commercial qualification | Frequently encountered as an accessible legacy Elbit Gen III commercial grade. The designation is a qualification level—not a statement that every XLSH will be low-performing or heavily blemished. |
| SLH | Commercial qualification | Commonly positioned above XLSH within commercial offerings, with stronger qualification requirements depending on the applicable production program. |
| PH | Higher commercial / performance family | A commonly encountered higher-grade legacy Elbit designation. Actual tube performance and cosmetics still vary individually. |
| YH | Aviation-oriented family | Appears within legacy Elbit 18 mm tube specification families and is associated with aviation-oriented requirements. |
| VH | Higher aviation-oriented family | Another published legacy Elbit qualification family with stronger requirements in applicable performance categories. |
| M16H | Military specification family | Defined legacy Elbit specification / qualification level within its 18 mm tube families. |
| M18H | Military specification family | Higher numerical qualification family within the legacy Elbit M-series structure. |
| M20H | Military specification family | Higher performance qualification family used across compatible legacy Elbit tube formats. |
| M22H | Military specification family | Higher qualification threshold within the published legacy M-series structure. |
| M24H | High military specification family | One of the higher published legacy Elbit qualification families encountered in premium / professional systems. |
It is tempting to turn the legacy Elbit nomenclature into one simple ladder: XLSH → SLH → PH → YH → VH → M24H.
That oversimplifies different qualification families and intended applications.
More importantly, an individual XLSH can exceed its minimums enough to outperform a nominally higher-grade tube in measured specs, cosmetics, or both.
F9400, F9415, F9800 and F9815
Legacy Elbit documentation identifies its 18 mm Gen III intensifiers with F-type part-number families. These codes remain relevant during the transition to Twenty-Six Defense.
These numbers are useful because they help identify the tube's format and phosphor configuration separately from its qualification grade.
| Legacy Elbit Family | Phosphor | Format | Gain Architecture |
|---|---|---|---|
| F9400 | White phosphor | MX-10160 | 10160-type configuration |
| F9415 | White phosphor | MX-11769 | Field-adjustable / external gain capable |
| F9800 | Green phosphor | MX-10160 | 10160-type configuration |
| F9815 | Green phosphor | MX-11769 | Field-adjustable / external gain capable |
Legacy Elbit documentation identifies MX-10160 tubes with the F9400/F9800 families and MX-11769 tubes with F9415/F9815. Exact configurations and available options should always be confirmed from the specific tube documentation.
ECHO, ECHO+, 4G and 4G+
Photonis—now part of Exosens—uses a very different technology and naming structure from L3Harris and Twenty-Six Defense / legacy Elbit.
This is important because Photonis tubes should not be evaluated by trying to force them into an L3-style 18 / 20 / 22 / 24 hierarchy.
Photonis emphasizes characteristics including fast autogating, small halo, high-light resolution, broad spectral response, contrast, and extended sensitivity in addition to traditional FOM and SNR.
| Photonis Family | Position | Published Performance | Key Characteristics |
|---|---|---|---|
| ECHO14 | Commercial | Approx. 1400–1800 FOM published range | Commercial technology with fast autogating, available phosphor options, and Photonis-style dynamic-light performance. |
| ECHO | High-performance commercial | Published ECHO specifications vary by current market/product documentation | Fast autogating, small halo, strong high-light performance, broad spectral response, and commercial pricing. |
| ECHO+ | Higher commercial selection | Up to approximately 2200 FOM in published Exosens documentation | Higher selected commercial performance while retaining Photonis dynamic-light and spectral characteristics. |
| 4G | Military / professional | 1800 minimum FOM; approximately 2100–2200 typical depending documentation | Fast autogating, very small halo, high highlight resolution, and extended spectral response. |
| 4G+ | Higher military / professional | 2300 minimum FOM; 30 minimum SNR; 72 lp/mm minimum center resolution | Higher performance qualification, very fast autogating and extended spectral sensitivity. |
Do not reduce Photonis versus Gen III to a simple FOM comparison.
Photonis technology can behave differently in mixed-light environments because of its autogating, halo characteristics, high-light resolution, spectral response, photocathode technology, and gain characteristics.
A tube with a lower FOM number can still offer characteristics that are highly desirable for a particular operating environment.
XD-4 and XR5
Used night vision equipment may also contain older Photonis families. These names remain relevant because there are still many functioning systems in circulation.
Earlier Photonis Technology
XD-4 represents an older Photonis technology family with broad spectral sensitivity and optional autogating.
Published Photonis data lists approximately 1200 minimum / 1400 typical FOM, 20 minimum SNR and 60 lp/mm minimum center resolution.
Higher Legacy Performance
XR5 represented a higher-performance Photonis family before the current ECHO / 4G structure became dominant.
Published Photonis data lists approximately 1600 minimum / 1770 typical FOM, 25 minimum SNR and 64 lp/mm minimum center resolution.
Understanding NVT-4, NVT-5, NVT-6 and NVT-7
NNVT-manufactured intensifiers have become increasingly common in the commercial night vision market, particularly as a lower-cost alternative to U.S. Gen III and European Photonis tubes.
The market commonly refers to families such as NVT-4, NVT-5, NVT-6 and NVT-7, with autogated variants frequently identified with an AG designation.
NNVT nomenclature requires extra caution because reseller grading, regional product naming, and available documentation are not always as standardized as the major U.S. manufacturer nomenclature.
| Family | General Position | Common Configuration | What to Know |
|---|---|---|---|
| NVT-4 | Entry / value family | Gated and autogated variants encountered | Common lower-cost modern Gen 2+ / multi-alkali option. Actual specifications should be checked individually rather than assumed from the NVT-4 name. |
| NVT-5 | Higher selection | Autogated variants commonly encountered | Generally marketed above NVT-4 with stronger performance selection. Exact specifications vary by source and production. |
| NVT-6 | Higher performance selection | Autogated variants | Higher market positioning than lower NVT families, but the actual tube record remains the correct way to evaluate performance. |
| NVT-7 | Higher-performance newer family | Fast autogating / extended spectral variants | Associated in the commercial market with higher SNR, 64+ lp/mm resolution, and extended near-infrared spectral response. |
| AG | Feature designation | Autogated | AG indicates an autogated power supply configuration. It is a feature designation—not an independent performance grade. |
Be especially careful with hard specification claims based solely on “NVT-4,” “NVT-5,” or similar labels.
Ask what the individual tube actually measures. SNR, resolution, gain, EBI, halo, phosphor, autogating, cosmetics, and the specific production configuration matter more than assuming every tube carrying the same NVT designation is identical.
10160 vs 11769
MX-10160 and MX-11769 are often incorrectly treated as quality grades. They are not.
They describe closely related 18 mm tube formats and, traditionally, the way gain control is implemented.
Fixed / Automatic Gain Format
The conventional MX-10160 architecture does not use the standard external gain-control pigtail associated with the MX-11769.
It is widely used in binocular and aviation-derived systems where conventional PVS-14-style external manual gain is not required.
External Gain-Control Format
MX-11769 was designed with field-adjustable gain capability and is closely associated with the PVS-14 architecture.
The traditional configuration uses an external gain-control interface or pigtail to communicate with compatible housing controls.
A 10160 is not automatically lower-grade than a 11769. A 11769 is not automatically higher-performing than a 10160.
The format tells you primarily how the intensifier interfaces with the device. The actual image and data record tell you how the tube performs.
Can 11769 and 10160 Tubes Be Converted?
Sometimes.
Because the underlying 18 mm intensifier architecture can be closely related, some tubes can be configured to operate in a housing designed around the other format.
But this is highly dependent on the manufacturer, power supply, gain-control architecture, tube generation, and housing.
Often Possible on Compatible Tubes
On certain 11769 tubes, the external gain-control architecture can be removed, replaced, or configured so the tube functions in a 10160-type application.
The exact method depends on the tube's power-supply design.
Sometimes Possible
The reverse conversion is possible with some tube architectures when the power supply provides a compatible gain-control interface.
It is not something that should be assumed possible with every 10160 tube.
Modern housing designs and newer gain-control systems make the old “10160 always means fixed gain / 11769 always means manual gain” rule less absolute than it once was.
Verify the exact intensifier and housing before assuming compatibility or conversion capability.
There Is No Universal Grade Ladder.
One of the biggest mistakes in night vision shopping is trying to build a single hierarchy from every manufacturer's nomenclature.
24UA, M24H, 4G+, ECHO+, and NVT-7 are not equivalent grades from different factories.
They come from different technologies, manufacturing processes, qualification systems, and intended applications.
“Gen 2+” and “Gen III” can describe broad technology families, but generation alone does not tell you how two individual modern tubes will compare.
A better comparison looks at the complete performance envelope: SNR, resolution, gain, EBI, halo, spectral response, autogating behavior, cosmetics, and the intended environment.
What Actually Matters?
Once you understand the nomenclature, the next step is evaluating the individual tube.
The designation tells you where the tube came from. The measured specifications tell you what that individual intensifier actually does.
Signal-to-Noise Ratio
SNR is one of the most useful indicators of how clean the image remains as available light decreases. Higher SNR generally means less visible noise and more usable detail.
Center Resolution
Measured in line pairs per millimeter. Resolution contributes to FOM, but more resolution alone does not automatically make a better tube.
Figure of Merit
FOM is SNR multiplied by center resolution. It is useful for broad classification but cannot describe every characteristic of image quality.
Equivalent Background Illumination
EBI relates to the tube's background output under extremely dark conditions. Lower values are generally desirable when operating near the lower limits of available light.
Halo
Halo describes the apparent bloom around bright light sources. Smaller halo can improve usable detail around lights and illuminated objects.
Luminance Gain
Gain describes how strongly the intensifier amplifies the available image. Comparing gain can be particularly important across different tube technologies.
Spots + Uniformity
A tube can have excellent numbers and still have cosmetics a buyer does not prefer. Spot location, shading, peppering, fixed-pattern noise, and uniformity all contribute to the viewing experience.
Spectral Response
Different photocathode technologies respond differently across the visible and near-infrared spectrum. This becomes particularly important when comparing Photonis-type technology with conventional Gen III.
Tube Matching
In binocular and panoramic systems, individual tube performance is only part of the equation. Closely matched brightness, gain, cosmetics, and performance characteristics can improve the complete system.
What the Acronyms Don't Tell You
“24UA Is Always Better Than 20UM.”
24UA has a higher qualification floor and different cosmetic acceptance requirements, but individual measured performance still matters.
“XLSH Means a Bad Tube.”
No. XLSH is a qualification designation. An individual XLSH can substantially exceed its minimums and can be an excellent tube.
“A Higher Grade Guarantees a Cleaner Image.”
Not necessarily. Qualification standards can influence allowable cosmetics, but the actual image of the individual tube is what ultimately matters.
“11769 Is Better Than 10160.”
No. Those are primarily format / gain-control distinctions, not performance grades.
“Gen III Automatically Beats Gen 2+.”
That is too simplistic for modern intensifiers. Tube technology, actual specifications and operating environment all matter.
“Higher FOM Always Wins.”
FOM matters, but it ignores several characteristics including halo, EBI, gain, cosmetics, spectral response and dynamic-light behavior.
Buy the Tube. Not the Label.
Quad Defense uses performance ranges to make configuring a night vision system manageable, but we do not treat the grade printed on an intensifier as the complete story.
Every QDEF-built system receives hand-selected intensifier tubes. We evaluate measured performance, image quality, cosmetics, and—when building binocular or panoramic systems—how well the intensifiers match as a complete set.
If a customer requires particular performance characteristics or has specific spot / cosmetic requirements, we can work directly with them to identify tubes within the selected performance tier that best fit those requirements.
The nomenclature tells you how the manufacturer classified the tube.
The individual specifications, image quality, cosmetics, compatibility, and intended use tell you whether it is the right tube for your system.
Acronyms are useful. The actual tube matters more.
RELATED INTEL //
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