Hydro Quip Replacement Heater For Cal Spas "Centered Style" Heater. You Will Notice This Heater Does Not Come With The Insulation Wrap That The Cal Spas Original Heater Came With. This Wrap Is Not A Necessary Component. This Heater Is Not An Exchanger, But An In-Line, Internal Element, Flow Thru Heater. It Is Designed As A "Drop-In" Replacement. 5.5kw, 240v. Flow Thru Heaters Are Said To Be Much More Efficient Than Heat Exchanger Styles. Comes With 2 Tail Pieces And 2 Gaskets. Replaces Cal Spas part numbers HEA14100430 and HEA14100455 (Balboa P/N 58278 and 58076). Thermcore or Therm Product part numbers F2550-2001 and C2550-2001-1.