Tork RKP504 208-277-Volt CFL Twist-Lock Photo ControlThe Photo Control is perfect for use on luminaries equipped with locking type receptacles, where most stringent surge protection is needed. It gives an added measure of security, feel of safety by automatically turning on your light at dusk and off at dawn. Photocell responds to the light spectrum near to that of the human eye. Easy to operate as it has delayed on and off response prevents false switching due to light from vehicles or lighting, etc.