Switchmaster SM300 central heating programmer and timer controller manufactured by Invensys Climate Controls. Features timed, off and constant operating modes with a 24-hour mechanical timer dial and removable wall-mounted control unit. Previously in service and reported as working before removal by a qualified electrician. Sold as untested as it has not been tested since removal. Clean condition with normal signs of age and use. Ideal replacement unit for compatible heating systems or for spares and repair purposes. Model: SM300 Brand: Switchmaster 230V 50Hz