Measure the outer edge of the flue tile and the crown top type to get the cap size and mount style. Always confirm with your local building code and the manufacturer.
Cap size: 8 in
Mount style: flue-mount
The cap's hood must sit at least six inches above the top of the flue opening to ensure proper draft and prevent smoke from backing up.
Measurement convention: outer-edge-to-outer-edge. Source: HY-C.
Verify with your local building code and the appliance manufacturer's manual before you build or buy.