Sweeps Perfection Single Flue Stainless Steel Rain Cap (fits outside flue tile size from) SP8X8 Fits Flue 6 1/2" x 6 1/2" up to 8 1/2" x 8 1/2" SP8X13 Fits Flue 8" x 11 1/2" up to 8 1/2" x 13 1/2" SP8X17 Fits Flue 8" x 15 1/2" up to 8 1/2" x 17 1/2" SP12X12 Fits Flue 10 1/2" x 10 1/2" up to 12 1/2" x 12 1/2" SP12X16 Fits Flue 10 1/2" x 14 1/2" up to 12 1/2" x 16 1/2" SP13X13 Fits Flue 11 1/2" x 11 1/2" up to 13 1/2" x 13 1/2" SP13X17 Fits Flue 11 1/2" x 15 1/2" up to 13 1/2" x 17 1/2" SP16X16 Fits Flue 14 1/2" x 14 1/2" up to 16 1/2" x 16 1/2" SP17X17 Fits Flue 15 1/2" x 15 1/2" up to 17 1/2" x 17 1/2" "Wow! My product arrived after three days. Thanks for the fast shipping, I am glad I ordered here. My friend ordered  from a different site and it took six weeks for the item to arrive!!! Keep up the good work." Mary Clarke, CA