Use this twist-to-lock photocell to automatically set lights to turn 'on' at dusk and 'off' at dawn in commercial and industrial outdoor settings. Use on sports fields, parking lots, commercial buildings, street lights or other NEMA locking plug type connection. Helps lower energy costs by only operating lights after dusk. The Woods brand of timers and home controls bring simplicity to your life, by maximizing convenience, security and energy savings.