replacement flo-thru hot tub spa heater element: 5.5kw, 4.5kw or 4kw - flow through spa depot 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.