PelletVent 3-6 in. Diameter Chimney Adapter, 3PVL-X6 at Tractor Supply Co.
DuraVent DuraBlack 6 in. x 8 in. Single-Wall Chimney Stove Pipe Slip Increaser 6DBK-XS8 - The Home Depot
SELKIRK 6" to 8" Black Smoke Pipe Adaptor (UltimateONE) – US Fireplace Store
Double Wall and Single Wall Stove Pipe Adapters - Rockford Chimney
Chimney Pipe, 8 inch, Single Wall to Double Wall Adapter, Class A, Insulated, Painted (Metal-Fab - Model 8TGPSWA) - Automotive Equipment Distributors | Automotive Tools And Equipment | Auto Lift Equipment | Hunter Wheel Alignment
DuraVent Pellet Vent Pro Chimney Adapter - 8" | 4PVP-X8 – North Country Fire
SuperVent 6-in x 6-in Stainless Steel Stove Pipe Adapter in the Stove Pipe Fittings department at Lowes.com
IMPERIAL 6-in x 8-in Black Steel Stove Pipe Increaser in the Stove Pipe Fittings department at Lowes.com
Multi-Floor Application 6 Inch DuraTech Chimney Kit
Dura-Tech 6" Chimney Adapter with Trim,for DVL or Single/Double Wall Stovepipe - Chimney Liner Depot
Amazon.com: DuraVent DVL 6DVL-X8 Double Wall Interior Stove Pipe Increaser to Vent Smoke & Exhaust, 6 Inch Diameter to 8 Inch Diameter Connection, Black : Home & Kitchen
Stove Pipe Adapter for 6" Single to Double Wall Insulated Chimney Pipe – Dominusheat
Chimney Adapter - Galvanized - 8 x 8 Square to Round with 6 Inch Collar | Luxury Metals