Precision T-19 - Lumatrol T-Series Wire-In Photo Control, 480 Volt, 2000 Watt Weatherproof Lexan housing Photocell: 1/2" cadmium sulfide light sensitive element. Turn-on: 1 to 3 foot-candles; Turn-on/off Ratio: 1:3 3" high, 2" wide, 1 3/8" deep Switch Type: Single-pole, single-throw. Contact position at night normally closed