MSA OptimAir 3000 Instructions For Use Manual page 8

Classifications
Table 2:
EN 166: Explanation of markings
Trade mark
1 Optical class
EN 166 EN standard
B Frame impact
3 Liquid splash
Table 3:
EN 397: Explanation of markings
440v ac Short term electrical contact
30°C Low temperature limit
Ld Progressive lateral forces
4
EN 166 1 B 3