Master Flow 6 in. to 5 in. Round Reducer R6X5 - The Home Depot
Grand Rock - 4", 5" or 6" Exhaust Reducer Pipe (Aluminized or Chrome) – Berube's Truck Accessories
Master Flow 6 in. to 5 in. Round Reducer R6X5 - The Home Depot
R6I-5IC 6 inch ID to 5 inch ID Reducer Chrome
Master Flow 6 in. to 5 in. Round Reducer R6X5 - The Home Depot
Reducer/Expander
Amazon.com: HG POWER 5 Inch Dryer Vent Hose, 16 Feet Long Flexible PVC Hose, Three Layer Noise Reducer Hose Aluminum Ducting for Heating Cooling Ventilation AC Exhaust Black : Appliances
5" OD to 6" ID 304 Stainless Steel Exhaust Tube Adapter Reducer 5" Length | eBay
6" x 5" OD-OD Exhaust Pipe Reducer Nelson 89883A
T-304 Stainless Steel Pool Concentric Reducer - 5 inch outlet - 6 inch inlet
Exhaust Reducer - 5" Inch < 6" Inch (Outside Diameter) – Exhaust Shop Australia
5.5 Inch OD X 6 Inch Flared Exhaust Adapter - Replaces J009393, T550-6, T5886 & 41654 - 4 State Trucks