inc vat exc vat
United Kingdom £ GBP

Shipping to
  • Price Match Promise
  • Free UK Delivery over £99 ex VAT
  • In-House Embroidery & Printing
  • 28-Day Returns
Standards guide · Eyes and face

Eye and face protection explained

Glasses have two markings: one on the lens, one on the frame.

  • EN 166:2001
  • EN ISO 16321-1:2022
  • EN 170
  • EN 172
  • EN 169
  • EN 379
  • EN 175

Read this ifYou see 1 F K N or 2C-1.2 on glasses

Decode the lens

Example lens: 2C-1.2 W 1 FT KN. The frame has its own marking (next graphic).

EN 166 lens
On the label
  1. 2C-1.2

    Filter (if any)

    Scale number for a filter lens. 2 / 2C = UV (EN 170), 5 / 6 = sun glare (EN 172), 4 = infrared, plain number = welding (EN 169). Clear impact lenses may have none.

  2. W

    Manufacturer's ID

    Letters or logo of the manufacturer.

  3. 1

    Optical class (1-3)

    1 = all-day wear. 2 = intermittent. 3 = occasional only, never long periods.

    1 low3 high
  4. F

    Impact (S, F, B, A)

    S = increased robustness. F = low energy, 45 m/s. B = medium, 120 m/s. A = high, 190 m/s.

  5. T

    Extreme temperatures

    Impact rating also holds at -5 C and +55 C.

  6. K

    Anti-scratch (optional)

    Resists surface damage by fine particles.

  7. N

    Anti-fog (optional)

    Resists misting.

  • Other optional lens letters: R = enhanced infrared reflection, O = original frame-fitted lens.

Decode the frame

Example frame: W EN 166 3 4 9 BT. Use the LOWER impact letter if frame and lens differ.

EN 166 frame
On the label
  1. W

    Manufacturer's ID

  2. EN 166

    Standard

  3. 3

    Field of use 3

    Liquid droplets or splashes (goggles / face shields).

  4. 4

    Field of use 4

    Large dust particles (over 5 microns) - goggles.

  5. 9

    Field of use 9

    Molten metal and hot solids - needs F, B or A impact too.

  6. B

    Impact (S/F/B/A)

    Spectacles can reach F at most. Goggles up to B. Face shields up to A.

  7. T

    Extreme temperatures

    As for lenses.

  • Other fields of use: 5 = gas and fine dust (gas-tight goggles), 8 = short-circuit electric arc (face shield). H on the frame = designed for small heads.
  • If no field-of-use number is shown, the eyewear is for general (mechanical) use only.

Impact: good / better / best

Example lens: 2C-1.2 W 1 FT KN. The frame has its own marking (next graphic).

EN 166 lens
On the label
  1. 2C-1.2

    Filter (if any)

    Scale number for a filter lens. 2 / 2C = UV (EN 170), 5 / 6 = sun glare (EN 172), 4 = infrared, plain number = welding (EN 169). Clear impact lenses may have none.

  2. W

    Manufacturer's ID

    Letters or logo of the manufacturer.

  3. 1

    Optical class (1-3)

    1 = all-day wear. 2 = intermittent. 3 = occasional only, never long periods.

    1 low3 high
  4. F

    Impact (S, F, B, A)

    S = increased robustness. F = low energy, 45 m/s. B = medium, 120 m/s. A = high, 190 m/s.

  5. T

    Extreme temperatures

    Impact rating also holds at -5 C and +55 C.

  6. K

    Anti-scratch (optional)

    Resists surface damage by fine particles.

  7. N

    Anti-fog (optional)

    Resists misting.

  • Other optional lens letters: R = enhanced infrared reflection, O = original frame-fitted lens.
Letter Speed Found on
S Robust Glasses
F 45 m/s Glasses, goggles
B 120 m/s Goggles, face shields
A 190 m/s Face shields

Tinted and UV lenses

UV filter lens: EN 170

Clear or lightly tinted lenses that block ultraviolet. Example: 2C-1.2.

EN 170
On the label
  1. 2C

    Code number

    2 = may affect colour recognition. 2C or 3 = good colour recognition.

  2. 1.2

    Shade number

    How dark: 1.2 (clear) up to 5 (dark). Most clear safety lenses are 1.2 or 1.7.

Sun glare filter lens: EN 172

Tinted safety lenses for outdoor work. Example: 5-3.1.

EN 172
On the label
  1. 5

    Code number

    5 = sun glare filter, no infrared requirement. 6 = sun glare filter with infrared requirement.

  2. 3.1

    Shade number

    1.1 (very light) to 4.1 (very dark). 4.1 is not for driving.

Welding

Example auto-darkening filter: 4/9-13 W 1/1/1/2 379.

EN 379
On the label
  1. 4

    Light state shade

    Shade before the arc strikes.

  2. 9-13

    Dark state shade(s)

    Shade range when the arc strikes. Choose by process and current - see the filter's chart.

  3. W

    Manufacturer's ID

  4. 1

    Optical class (1-3)

    1 = best.

    1 low3 high
  5. 1

    Diffusion of light (1-3)

    1 = least scattering.

    1 low3 high
  6. 1

    Variation of shade (1-3)

    How even the shade is across the lens. 1 = best.

    1 low3 high
  7. 2

    Angle dependence (1-3)

    How the shade changes when viewed at an angle. 1 = best. Optional.

    1 low3 high
  8. 379

    Standard

    EN 379 auto-darkening filter.

  • Fixed passive welding filters (EN 169) show one shade number, e.g. 11. The helmet shell was tested to EN 175 (now being replaced by EN ISO 16321-2 for welding).

Good to know: EN 166 is being replaced

  • The new standard is EN ISO 16321-1.
  • New labels look different.
  • EN 166 stock is still fine to use.

Which do I need?

Which eyewear?

  • Flying bits?F glasses
  • Grinding or high speed?B goggles or A face shield
  • Chemical splash?Goggles marked 3
  • Dust?Goggles marked 4 or 5
  • Outdoors?EN 172
  • Welding?Filter shade for the process

Common mistakes

  • Glasses for chemical splash. You need goggles marked 3.
  • Ignoring the lower letter. Frame F + lens B = F.
  • Optical class 3 for all-day wear.
  • Dark tint indoors.

The law

  • PPE at Work Regulations 1992. COSHH 2002 for chemical splash.

Shop Eyes and face

All EN 166EN ISO 16321Medium impact B
GogglesFace shieldsOver-specs
UV EN 170Sun glare EN 172Anti-fog

Frequently asked questions

What does F mean on safety glasses?

F is low energy impact, 45 m/s. S = robust, B = 120 m/s, A = 190 m/s.

Can I use safety glasses for chemical splash?

No. You need goggles marked 3.

Is EN 166 still valid?

EN 166 is being replaced by EN ISO 16321-1. New labels look different. EN 166 stock is still fine to use.

More guides