This post contains affiliate links. As an Amazon Associate I earn from qualifying purchases This thermal regulator is designed to use with Pentair Sta-Rite Max-E-Therm pool and spa heaters and also compatible with Pentair MasterTemp pool and spa heaters. Product Features Thermal Regulator Replacement Fits Pentair Sta-Rite Max-E-Therm Pool And Spa Heaters Also Fits Pentair