| Model Size | Fits Minimum Inside Flue Sizes | Fits Maximum Inside Flue Sizes |
| 8" x 8" | 6" x 6" | 9" x 9" |
| 8" x 17" | 6" x 14" | 9" x 17.5" |
| 9" x 13" | 7" x 9" | 8" x 12.5" |
| 13" x 13" | 9" x 9" | 12.5" x 12.5" |
| 13" x 18" | 9" x 14" | 12.5" x 17.5" |
| 18" x 18" | 14" x 14" | 17.5" x 17.5" |