This Tesla Immersion Heater features a 1 3/4" head and is suitable for both hard and soft water areas. It is designed for use with copper and stainless steel cylinders. The heater includes a dual safety thermostat and an integral safety cut-out to prevent overheating, with a manual reset. It is an All Incoloy Immersion Heater & Plug In Stat, measuring 14 inches with a 1 3/4" Boss Steel. It operates at 240V - 3kW (230V - 2.7kW) and is suitable for Stainless Steel unvented cylinders. The unit comes complete with a dual safety plug-in thermostat and O-ring.