Mission Clay Products makes a full line of square and rectangular flue liners in one- or two-foot lengths.
1'
2'
8" x 8"
168
120
64
72
48
36
24
24
84
48
32
24
18
12
8" x 13"
8" x 17"
13" x 13"
13" x 17"
17" x 17"
20" x 20"
24" x 24"
8" x 8"
13" x 13"
13" x 17"
17" x 17"
Cast Iron Clean Out
Ash Dump
8 x 8
9 x 4