Summary (as of 27.10.2026)
The safety glasses marking according to EN 166 reveals what a pair of glasses is tested for: on the lens and the frame are symbols for optical class, mechanical strength (S, F, B, A) and areas of use (3 liquids, 4 coarse dust, 5 gas and fine dust, 8 electric arc flash, 9 molten metal). According to DIN Media, DIN EN 166:2002-04 has been withdrawn since 2026-06 and replaced by DIN EN ISO 16321. The risk assessment determines which glasses a company needs.
Splinters during grinding, splashes during decanting, dust during sawing: the eyes are exposed to danger unprotected in many tasks, and damage is often irreversible. Eye protection is therefore part of the basic equipment. But not every pair of glasses protects against every danger. The answer is on the glasses themselves, in a chain of numbers and letters.
This guide explains in tables how to read the marking of safety glasses, what has changed in the 2026 standard, and which glasses are suitable for which hazard.
Why is the safety glasses marking so important?
According to DGUV Rule 112-192 "Use of eye and face protection", an eye protection device only provides sufficient protection if the appropriate lenses are in the appropriate frame. The lens and frame are marked separately. If both are part of a single unit, the complete marking is on the frame. In addition, eye protection must be marked with the CE marking.
Standard 2026: EN 166 is replaced by EN ISO 16321
Until now, EN 166 was the basic standard for eye protection. According to DIN Media, DIN EN 166:2002-04 has now been withdrawn. It is replaced by the standard series DIN EN ISO 16321 "Eye and face protection for professional applications", which was published in June 2026:
| Standard | Content |
|---|---|
| DIN EN ISO 16321-1:2026-06 | General requirements, replaces among others DIN EN 166:2002-04, DIN EN 170 and DIN EN 379 |
| DIN EN ISO 16321-2:2026-06 | Additional requirements for protective devices for welding and related processes |
| DIN EN ISO 16321-3:2026-06 | Additional requirements for protective devices made of fabric (basket and mesh devices) |
According to DIN Media, the new standard brings among other things these changes: Eye protection against electric arc flash is no longer within the scope, IEC 62819 applies here. Interchangeable parts must be easy to mount without tools, and physiological compatibility has its own section. The symbols in the following tables come from DGUV Rule 112-192 on EN 166 and can be found on existing glasses. For newly purchased glasses, check which standard the manufacturer uses for marking.
Reading the lens marking
On the lens are, in this order, the protection level (only for filtering), the manufacturer's mark, the optical class, and if applicable, symbols for strength and additional properties. The optical class describes the visual performance:
| Class | Meaning |
|---|---|
| 1 | for work with particularly high requirements on visual performance, also for continuous use |
| 2 | for work with average requirements on visual performance |
| 3 | only in exceptional cases for rough work, not for continuous use |
The mechanical strength shows which impact the lens withstands. It is tested with steel balls:
| Symbol | Meaning | Test |
|---|---|---|
| none | basic mechanical strength | static deformation test |
| S | increased mechanical strength | 43-g steel ball at 5.1 m/s |
| F | low-energy impact | 0.86-g steel ball at 45 m/s |
| B | medium-energy impact | 0.86-g steel ball at 120 m/s |
| A | high-energy impact | 0.86-g steel ball at 190 m/s |
Three more symbols can be added: 9 for molten metal non-adhesion, K for the resistance of the surface to damage from small particles (scratch resistance) and N for resistance to fogging.
For filtering, the protection level is added, consisting of a prefix and the protection level number. The higher the protection level number, the lower the transmission of optical radiation. The prefix means: 2 for UV filters, where color recognition can be affected, 3 for UV filters with good color recognition, 4 for infrared filters, 5 for sun protection filters without and 6 for sun protection filters with infrared protection requirements.
Frame marking: What is the pair of glasses intended for?
The symbol on the frame describes the area of use. Important: A frame without a symbol only covers unspecified mechanical risks as well as radiation.
| Symbol | Designation | Area of use |
|---|---|---|
| no symbol | unspecified | unspecified mechanical risks, ultraviolet, visible and infrared radiation as well as solar radiation |
| 3 | liquids | drops and splashes |
| 4 | coarse dust | dust with a particle size above 5 µm |
| 5 | gas and fine dust | gases, vapors, mists, smoke and dust below 5 µm |
| 8 | electric arc flash | electric arcs during short circuits in electrical systems |
| 9 | molten metal and hot solids | molten metal splashes and penetration of hot solids |
The frame can also bear the strength symbols F, B or A, then the letter stands after a hyphen. The safety glasses marking always applies to the combination of lens and frame: the weaker of the two specifications limits the protection (Technigro's classification).
Which safety glasses are suitable for which hazard?
DGUV Rule 112-192 assigns the hazards to the markings:
| Hazard | Suitable eye protection |
|---|---|
| chips and splinters (mechanical) | safety lenses with S, F, B or A, depending on the kinetic energy |
| liquid splashes into the eye | full face shield with marking 3 |
| gases, vapors, mists, smoke, fine dust below 5 µm | full face shield with marking 5 |
| liquid splashes on face and neck | protective shield (visor) |
| molten metal splashes | eye and face protection with marking 9 |
| short circuit arcs | only visors with marking 8, without exposed metal parts |
In the range you will find temple glasses, full face shields (basket shields), visors and combinations as well as accessories for eye protection. Our classification: temple glasses are suitable for general mechanical hazards, full face shields enclose completely and are suitable for splashes, gases and fine dust, visors additionally protect the face. For welding work, separate requirements apply, suitable equipment can be found at welding protection.
Fit, care and replacement
- Check lenses for scratches, cracks and damage before each use, because they impair vision and strength.
- Replace scratched or fogged lenses if visual performance suffers.
- Note that the lens and frame must fit together, do not mix parts from different manufacturers without approval.
- Clean and store glasses according to the manufacturer's instructions, keep them protected.
- Ensure a good fit: glasses that press, slip or fog will not be worn.
- Combine eye protection with other PPE only if everything fits tightly and comfortably together, for example with head and hearing protection.
Checklist for purchasing safety glasses
- hazard defined according to the risk assessment (splinters, splashes, dust, gases, radiation, molten metal)
- area of use on the frame suitable (3, 4, 5, 8, 9) and strength F, B or A selected
- optical class suitable for the activity (Class 1 for continuous use)
- additional symbols K and N for dust, scratches and fogging considered
- CE marking and standard designation (EN 166 or EN ISO 16321) checked on glasses and packaging
- fit and compatibility tested in a try-on test
- instruction planned, replacement and care rules established
Eye protection at Technigro
At Technigro you will find eye protection for companies from temple glasses to visors. Companies order with the B2B program via a company account. Further markings from A to Z are explained in the PPE lexicon, an overview of categories and standards is given by the post choose PPE correctly: what lies behind the standards. How head protection and visors complement each other is shown by the post Head protection for construction workers: helmet, EN 397 and selection.
Who can read the safety glasses marking chooses eye protection specifically according to the hazard instead of appearance.
Note: This post informs generally (as of 27.10.2026). Which protective equipment is required is determined by the risk assessment of your company. In case of doubt, clarify the selection with your occupational safety specialist.
Sources
- DGUV Rule 112-192 "Use of eye and face protection", Section 3.2.4 Marking (text reproduction BG BAU). Retrieved on 27.10.2026.
