EN353-2 relates to systems made up of a line intended to be fixed (either temporarily or permanently) to a structure at the top only, on which a travelling device is attached. The user connects to this travelling device when climbing or descending – in the case of a fall, the travelling device should grip the line and arrest the fall.

1) Optical Requirements

Tests include: transmission and diffusion of light, refractive properties, resistance to aging (stability to heat and resistance to UV), corrosion and ignition. Results of the testing define the Optical Class of the eye protector: which falls into 1 of 3 categories, where 1 is the highest and 3 is the lowest as indicated in the table. These categories define the quality of the lens in terms of how much or how little distortion is experienced by the wearer.

2) Mechanical Protection / Impact Resistance

This test (applicable to both lens and frame) determines the impact resistance of the eye protector (spectacles, goggles or visors) to withstand flying objects without cracking or shattering. The test is performed with steel balls of different diameters and weights which are used to strike the lens and frame at different speeds as indicated in the table. This results in 4 levels of mechanical protection denoted by the markings; 'S' 'F', 'B' or 'A' on the eye protector where 'S' is the lowest grade, offering the least amount of protection and 'A' is the highest grade offering maximum protection under the standard.

Note: spectacles can only get a S or F marking, goggles can have a S, F or B, whereas grade A is applicable to visors only.

EN 166 also describes other optional tests which must be applied should the manufacturer wish to make additional claims regarding protection. For example, the Impact Resistance Against High Speed Spectacles At Extreme Temperature is conducted on spectacles/goggles and visors conditioned at extreme temperatures from -5°C / +55°C, resulting in similar markings as the above table, with a T denoting temperature: FT / BT / AT. Note: This does not apply to the S marking category.

See the table to the left to see other optional requirements and their corresponding markings for EN 166.