The RB-120 is a photocell with twist and lock photo control. Ideal for illuminating large area spaces. High impact polycarbonate cover with UV resistant acrylic window. Heavy duty bi-metal switch. Light sensor is a 1/2" cadmium sulfide cell. Temperature range -40C to 65C. Turn On 1.5FC, Off/On ratio 4:1. 30-45 second off and on time delay.