EN 166:2002 is a European technical performance standard for eye protection. All manufacturers of safety eyewear are required to have their products independently tested against this European standard. Both the frame and lens are tested, therefore both must include the CE symbol and the manufacturer’s logo. The CE marking certifies that a product has met EU consumer safety, health or environmental requirements.

Within the standard, there are numerous levels of compliance, depending on the end use of the piece of equipment in question.

A: MARKING ON FRAME

III. Field(s) of use (where applicable):

• 3: Protection against liquids (droplets or splashes).
• 4: Protection against large dust particles.
• 5: Protection against gases and fine dust particles.
• 8: Protection against short circuit electrical arcs.
• 9: Protection against molten metal and hot solids.

IV. Mechanical Strength/Resistance Symbol:

• S: Increased robustness (low energy impact, 5.1 m/s). 
• F: Low-energy impact (45 m/s). 
• B: Medium-energy impact (120 m/s). 
• A: High-energy impact (190 m/s). 

B: MARKING ON LENS

VI. Scale Numbers:

Filter Type Code:

• 2: UV filter
• 2C or 3: UV filter with good colour recognition
• 4: Infrared Filter
• 5: Sunglare filter
• 6: Sunglare filter with IR specification

Scale Number (Shade):

• 1.2: Clear or Amber
• 1.4: Blue or I/O Waterproof
• 1.7: Minimises or I/O
• 2.5: Grey Revo
• 3.1: Dark Grey or Mirror

VIII. Optical Classes:

• Class 1: Continuous work. Can we worn at all times (e.g., safety glasses for prolonged use).
• Class 2: Intermittent work. Should only be worn for occasional use (e.g., goggles for short tasks)
• Class 3: Should not be worn for long periods (e.g., face shields for brief exposure)

IX. Mechanical Strength/Resistance Symbol:

• S: Increased robustness (low energy impact, 5.1 m/s). Eye protection type: Spectacles
• F(T): Low-energy impact (45 m/s). Eye protection type: Faceshields/Googles/Spectacles
• B(T): Medium-energy impact (120 m/s). Eye protection type: Faceshields/Googles
• A(T): High-energy impact (190 m/s). Eye protection type: Faceshields

• T: Resistance to impact at extreme temperatures (-5°C to +55°C) when combined with F, B, or A.

X. Field(s) of use (where applicable):

• 3: Protection against liquids (droplets or splashes). 
• 4: Protection against large dust particles. 
• 5: Protection against gases and fine dust particles. 
• 8: Protection against short circuit electrical arcs. 
• 9: Protection against molten metal and hot solids.

XI. Resistance to surface damage by fine particles

K: Scratch-resistant coating

XII. Anti-fog properties

N: Anti-fog coating to prevent condensation

ADDITIONAL MARKINGS

Welding Filer:

• 1.7: Welding Assistant
  
• 3-5: Brace Welding
• 5-7: Oxy Cutting
• 7+ Other Welding

Ultraviolet (UV) Protection:

• U2: Low-level UV protection
• U3: Moderate-level UV protection.
• U4: High-level UV protection.
• U5: Very high UV protection.
• U6: Maximum UV protection (blocks nearly all UV radiation up to 400 nm).

Visible Light Filtering (Shades):

• L1.3: Low tint (light shade). 
• L1.7: Slightly darker than 
• L2.0: Moderate tint. 
• L2.5: Moderate to dark tint. 
• L3.0: Dark tint (used in bright environments). 
• L4.0: Very dark tint (for environments with extreme brightness).

Infrared (IR) Protection Markings:

• I1: Low-level IR protection. Provides basic protection against infrared radiation.
• I2: Moderate-level IR protection. Offers moderate protection against infrared radiation exposure.
• I3: High-level IR protection. Designed for tasks with significant infrared radiation exposure, providing strong protection.
• I4: Very high IR protection. Offers maximum protection from infrared radiation, suitable for environments with intense heat or infrared radiation.