When aligning a laser system you have to be able to see the beam. EN 208 solves that: it specifies eyewear that keeps the beam visible while attenuating it to class 2 levels (0.4–1 mW), where the eye's natural blink reflex provides sufficient protection.
Marking
The marking uses an R-number (RB1–RB5) together with the wavelength range — 532 RB3, for example.
A critical warning: EN 208 eyewear does not replace EN 207. It is for alignment at reduced power only. Full-power operation requires eyewear certified to EN 207.