In-wall, 7-day, digital, astronomic timer. Programmable timer switch automatically turns lights on/off based on a pre-set 7-day schedule with astronomic feature that allows you to automatically adjust dusk to dawn times. Program up to 18 on/off schedules per week. Each program can be unique or repeated daily, by weekends, or by weekdays. Random function varies the schedule for a lived-in look. Timer switch automatically adjusts for daylight savings time. Back-lit LCD (liquid crystal display) screen activates when a button is pressed. Helps to easily read and program timer switch in dark areas. Includes battery back-up. Compatible with CFL (compact fluorescent), LED (light emitting diode), and incandescent light bulbs.