Optimum Electronic Boost Timer Universal 15 Mins - 2 Hour Immersion Heater Energy Saving. This timer allows for timed regulation of any mains electrical load with a resistive rating of up to 16 amps. It is designed to fit onto a standard in-wall pattress box and offers timed outputs of 15 minutes, 30 minutes, 1 hour, and 2 hours. Connections are made using 4 wire-protect screw terminals and an earth park. Features include a T45 Temperature Rating, 16A Resistive Output Rating, IP20 Rating, and a 220 - 240V AC 50Hz power supply.