Pentair 472508 40-Volt Transformer Replacement MiniMax Pool and Spa Heater Transformer replacement Fits Pentair MiniMax NT STD Heater with 6800 Controller, DDTC Controller pool and spa heater models 200, 250, 300, 400 Also fits Pentair MiniMax NT LN Heater with 6800 Controller, DDTC Controller pool and spa heater models 200, 250, 300, 400 Compatible with Pentair MiniMax NT TSI Heater with 6800 Controller, DDTC Controller pool and spa heater models 200, 250, 300, 400