Optimum Pool Technologies High Limit Switch Replacement for Pentair MasterTemp & Max-E-Therm Heaters - Replaces 42001-0063S Replacement High Limit Switch (135F) for Pentair Sta-Rite MasterTemp & Max E Therm Pool Heaters Replaces Part No. 42001-0063S & STA-151-6255 Compatibility: Pentair MasterTemp (All Models) & Max-E-Therm (Models SR200, SR333, SR400) Heaters Manufactured by Optimum Pool Technologies