K4000 Series fixed position mounting photo control is thermal-type photo control that fit into a standard outlet box, post lamp, or wall pack. The photo controls provide dusk-to-dawn lighting control along with a delay action, which eliminates loads switching OFF due to car headlights and lightning. The thermal-type controls feature a cadmium sulfide photocell and a sonic-welded polycarbonate case and lens to seal out moisture. The design utilizes a dual temperature compensating bimetal and composite resistor for reliable long life operation over ambient temperature extremes. Cadmium sulfide photocell. Sonic-welded polycarbonate housing and lens to seal out moisture. Delay action eliminates load switching OFF due to car head lights and lightning. 9 inch leads. Most models equipped with a 5/8 - 18 inch threaded side mounting, locking nut and washer gasket.