Pentair 460507 5-Inch Indoor Vent Adapter Replacement Kit MiniMax NT Pool and Spa Heater 5-inch indoor vent adapter replacement kit Fits MiniMax NT STD and NT TSI heater with 6800 controller models 200, 250, 300, 400 Also fits MiniMax NT STD, NT LN and NT TSI heater with DDTC controller models 200, 250, 300, 400