Selkirk 3"/4"/5" Double Wall Increaser (Round - Type B Gas Vent) Size:3" to 4" it is almost as efficient

it is almost as efficient as a single wall black pipe

Model 7DT-09SS Series DuraTech DT (5"-8") Product Type Chimney Pipe Inner Finish

The Symmetry extra tall Bespoke fireplaces are perfect for any commercial or residential space

Instant Ambiance: Arrange driftwood and rocks in any pattern for a custom look

Selkirk 3"/4"/5" Double Wall Increaser (Round - Type B Gas Vent) Size:3" to 4" it is almost as efficientSelkirk 3" 4" 5" Double Wall Increaser (Model RV Type B Gas Vent) Used to increase pipe diameter. (RV) Round Type B Gas Vent Model RV Double Wall Gas Vent is the installer's choice for residential, industrial and light commercial applications. The aluminum liner heats up quickly to promote strong draft. Galvanized outer provides protection against outdoor elements. Product line includes DWC Double Wall Connectors and EFC Expandable Flex Connectors.