Universal Flo-Thru Heater Element is available in 4.0 kw with selection for Titanium. This replacement heater element fits any spa controllers or spa packs that takes a universal hi-flo element including products made by Balboa, Gecko, Spa Builders, Hydro Quip, ACC, Acura Spas, Len Garden, Coleman, Watkins, Dimension One, and many others. The heater housing must be a Flo-Thru metal tube, at least 12 inches long, and at least 2.25 inches in diameter. The heater terminals should be more towards one side of the heater tube. Dimension (Approx.): 10 inches long, 1.37 inches across and normally used in a 15 inch long Flo-Thru heater metal tube that is at least 2.25 inches in diameter (also known as 2 inch heaters). Heater elements made out of Titanium metal. It provides the best heat to water transfer. Its made to withstand many water conditions that other heater elements cant. Titanium is known to be the most non-corrosive, longest lasting, and not too many particles will stick to it. The 4.0KW Heater Element is also an optional replacement for the following Heaters: C2400-0304, C2400-1054, C2400-0535, C2400-0809, C2400-0321, C2400-0165, 20-00518, C2400-2315, C2400-0307, C2400-0002, C2400-0073, C2400C2550-2, C2400-0313N, C2400-0213N, C2400-0256, C2400-0056, C2400-0000, C2400-1227, C2400-1206, 25-150-1025, C2400-5000-2, 25-175-8104, 58104, 58271, 58173, C2450-0802ET, C2450-0802, HEP-00-00-0037835, HEP-00-00-00 or 73994 or C2400-C3330-1 or C2400-C3330-1A (Caldera Spas), C2450-0802, 58269, 25-250-2020, 25-175-8173, 25-250-1004, C2400-1206 (13in), HEA14100041, 20-00278-C, C2400-0309, C2400-5000-1, C2400-5000-2B, 58148, 55033, 55033-01, 55033-02, 55035, 55035-01, 58109, 102372 or 54598 (Coleman), 58117, 12-0102-K, 12-0102-G, BX5000CT, BX5000C, 47-555-2525, 47-555-2075, 58048, C2400-1004, C2400-1004TI-1, C2450-1004, B24040KX, C2400-1004TI, 25-175-8269, 25-175-8271, B24045G (4.5KW), 20-00422 (4.5KW), C2450-0521 (4.5KW).