The Terma TS1 element probe is designed to work in combination with the KTX Range of Controllers to provide a fully functioning heating element. Timer options will be determined by the model of KTX Controller this probe is paired with. Straight cable, no plug. Class 1. 285mm internal probe length. Wattage Selection Advice: For wattage look at the output of the chosen rad as c/heating in watts and choose an element with the wattage closest to that figure. For BTUS the conversion formula is BTUS / 3.41 = Watts. Electrification Advice: When making the decision to electrify any towel rail or radiator it is important to check with the manufacturer of that model that it is suitable to work with a heating element. Not all towel rails or radiators are suitable. Dual Fuel Advice: If you are buying a heating element to convert a towel rail for use as dual fuel (electric in the summer and central heating in the winter) it is important to remember to regularly bleed the towel rail, as on a central heating system air can build up inside. A heating element should never be run in the open air as this could potentially cause the surface of the rail to get extremely hot and burn your towels.