Premium grade flow-through replacement spa heater elements. You cannot buy a better quality hot tub heater element at any price. Fits 2" stainless steel flow thru tube spa heater manifolds including Balboa M-7, Brett Aqualine, and many others. Use 2 wrenches when connecting to avoid damage. Replaces 12-0100-K (5.5kW), 12-0101-K (4.5kW), 12-0102-K (4.0kW), 6-flo, 4-FLO 25-4030, 20-3440, 25-4044.