Smart safe divers know that one is none and two is one. Dive Rite's conveinent backup lights offer impressive depth ratings of up to 600 fsw and illummination time of up to 100,000 hours. All backup lights come standard with a twist actuator to turn the light on and off. Feel confident with a secondary light from Dive Rite. Contact your authorized Dive Rite dealer to help you purchase the light most specific to your diving needs.