These Phillips and Temro (Wolverine) Zerostart Filter heaters are designed for pre-heating fluids which are prone to freezing or thickening in low temperatures, such as Diesel or oils. The heater wraps closely around the filter body and attaches using the supplied hook and loop straps. The heater pad is powered via either a 12v or 24v feed, depending on the model, so can be wired to the vehicle electric system and operated via a switch.Easy to attach using the supplied hook and loop strapsIdeal for Diesel filters to allow for easier engine starting in cold conditions12v or 24v power supply so it can be run of the vehicles supply (Check the table below for operating voltage)Low wattage and energy efficientPhillips and Temro (Wolverine) filter heaters have a simple 2 wire hook up and are not polarity sensitive. They should be wired through a fuse for circuit protection.Please Note: Some heater pads will be branded Phillips and Temro and some will be branded Wolverine but they are the sam