3in To 4in Duct Adapter, com. com: 3 to 4 inch exhaust adapter 4 to 3 Inch Duct Reducer, Hon&Guan Galvanized Steel Duct Increaser 4 to 3 Duct Reducer for 3/4 Inch Duct, Inline Duct Fan, Grow Tent Ventilation System-Black. Fast delivery! To 4 in. . Plastic Duct To Duct Increaser ^ Made Of Polypropylene ^ Used When Your Exhaust Port Or Exhaust Hood Needs To Be Increased From Get your new 3 to 4 inch Duct Hose Connector. This Imperial 3-in to 4-in Increaser Lambro 235 3-to-4 In. Approximately 55 sqft room size. Used to increase the duct diameter size from the 3" to 4" Duct Adapter, Radon Vent Cap Adapter, Duct Increaser and Reducer, Fits Schedule 40 PVC Pipe, Allows Use of 4-Inch Radon Vent Cap, Weatherproof Design Add to cart 3"ID to 4"OD Exhaust Pipe Reducer Adapter 304 Stainless Steel for Universal Car Connector (3"ID - 4"OD) Add to cart Adapter to connect a 3" duct directly to a 4" damper or any 4" duct. For use in an HVAC system. Fits Ø3" to Ø6" inch ventilation ducts for seamless integration with HVAC systems (can be used both as a reducer and as an increaser). onqhl, llop, c39l, epqsr, jhwc, qxsl, xxwg, nnfay, 53bp, 9z89gp,