Use at top of existing chimney to convert Co-Linear tubes to Co-Axial AmeriVent Direct on Travis units, but may fit on other models and manufacturers based on measurements

Measurements: 
Size: 4" x 6 5/8"
A: 11"
B: 9"
C: 4"
D: 3" Diameter 
E: 3" Diameter 

As per this manufacturer's policy, we cannot sell parts provided by Travis Industries, outside of out selling territory in New England