The HET01-H1 is an in-wall digital timer switch with astronomic programming features. The astronomic features calculate dusk and dawn times based on the time of year and geographic location to ensure that any dusk/dawn program settings are accurate. This astronomic timer switch allows users to program and save up to 7 unique pairs of ON/OFF settings. Program unique lighting schedules for all days of the week, individual days of the week, weekdays-only, or weekends-only. The digital timer adjusts for daylight savings time automatically and it includes a random mode that can be used for extra security when away on vacation. It features a large LCD screen with backlighting and a built-in battery pack that retains saved programs in the event of a power outage. A manual override button allows the load to be turned ON/OFF at any time. The astronomic timer switch is compatible in either single pole or three-way installations. This device works with incandescent, halogen, and LED lights, which make it ideal for either indoor or outdoor use.