Pentair METAL FLUE COLLAR 4 x8 Replacement Pool Part Pentair METAL FLUE COLLAR 4 x8 (77707-0077) The Metal Flue Collar is an adapter part that s used to connect a negative-pressure metal gas vent to the heater. Fits most vent sizes on MasterTemp Heaters: 200 250 300 and 400 as well as Pentair Sta-Rite Max-E-Therm pool and spa heaters. Includes a 4-inch by the 8-inch collar. Also includes one tube of Loctite SI 596 RD red high temp RTV Silicone Adhesive Sealant.