This plug-in 24-hour single channel mechanical timer from Baxi is for the new 200 series and 400 series combi boilers and offers a choice of functionality constantly on, constantly off or timed operation to improve the energy efficiency of your boiler and the overall performance of your heating system. Switching is made easy in 15-minute adjustable time segments using tappets set around the face of the timer. Compatible with the Baxi 200 series and 400 series combi boilers only. Baxi 200 & 400 Series Plug-in 24 Hour Single Channel Mechanical Timer