The order of markings on frames where relevant is: Manufacturer’s mark; EN166; Fields of use; Mechanical strength.

Markings associated with the basic requirements only – for all protective eyewear:

Requirement	Lens Symbol	Frame Marking
Scale Number or Shade Number	Required for filters only	–
Manufacturer’s Identification	Required	Required
Number of the Standard		EN 166
Optical Class	1, 2 or 3
Mechanical Strength Minimum Robustness Enhanced Robustness If high-speed particle testing requirements are met, the S symbol is replaced by one of the symbols below. Low Energy Impact Medium Energy Impact High Energy Impact	No symbol S F B A	No symbol S F B A

Particular/optional requirements and associated markings:

Requirement	Lens Symbol	Frame Marking
Droplets or splashes of liquids		3
Large dust particle		4
Gas and fine dust particle		5
Short circuit electric arc	8	8
Molten metals and hot solids	9	9
Resistance to surface damage by fine particles	K
Resistance to fogging	N
Enhanced infrared reflectance	R
Replacement oculars	o

Some of the tests in the above table are not suitable for all eyewear types. For example, the only valid tests for spectacles are those with a letter K, N or R. Spectacles cannot be tested for liquid splash or large dust particles, as they are unable to protect against those hazards.

The resistance to high-speed particle test is carried out on complete eyewear. It tests the oculars and the frame. The particle used for these tests is a 6mm diameter steel ball-bearing that weighs 0.86g.

Low energy impact (at a speed of 45m/s) is applicable to all types of protective eyewear, but the medium energy impact (at 120m/s) is only applicable to goggles and face shields.

The high energy impact test (at a speed of 190m/s) is only used for face shields. This test is usually carried out with the samples at ‘normal’ temperatures but can be carried out in extreme temperatures. In this version of the test, the eyewear is impact tested after conditioning at 55°C and -5°C.

EN166 Marking