Laser Class

Laser class rates the potential hazard of the laser beam to your eyes. Construction lasers are Class 2 (up to 1 mW) or Class 3R (up to 5 mW). Class 2 lasers are safe for brief accidental exposure because your blink reflex protects you. Class 3R lasers are more visible outdoors and at longer distances but can cause eye damage if you stare directly into the beam. Industrial and scientific lasers go up to Class 4, which burns skin and ignites materials. You won't find Class 4 at a hardware store. For indoor work, Class 2 is bright enough. For outdoor work in daylight, you'll want Class 3R or a laser detector.