Drayton SM1 is a single-channel programmer. Utilising the more traditional rotating time wheel with pegs for settings, this easy-to-understand mechanical timer is suitable for use on most domestic pumped and gravity central heating systems. Drayton's SM1 single channel 24 hours electro-mechanical time switch gives style and ease of use to suit most domestic combination boiler systems.

• "Designed for combination boilers, Advance feature, For ease of use, a four-position slide is provided, Two on or off periods per day, Industry standard wall plate, Manufactured in UK, All day option, Fits on a universal backplate"