New Honeywell ST9100 Timer. Single channel 1 day timer, for control of a single heating zone or a combi bolier. Features: LoT display, providing text feedback that gives help and programming hints. Large backlit display (57 x 37mm) Factory set clock and date. Automatic Summer/Winter time change. 2 on/off periods. Tempory or permanent override faciltiy. Extra hour facility, for up to 3 hours of boost or programme extension. Fits on Industry standard back plate. Direct replacement for ST6100 model Suitable for mains, low voltage or potential free switching.