Each size of windsail is designed to be matched with one of our Corinthian Bells® Windchimes. The T106 sail (with a 4" diameter) fits our 27" windchime; the T206 sail (with a 4.5" diameter) fits our 30" windchime; the T306 sail (with a 5" diameter) fits our 36" windchime; the T406 sail (with a 5.5" diameter) fits our 44" and 74" windchimes; the T516 sail (with a 6" diameter) fits our 50" windchime; the T736 sail (with a 7" diameter) fits our 56", 60" and 65" windchimes; and the T936 sail (with a 8.75" diameter) fits our 78" windchime. All the diameters listed are approximations and the lengths are the overall lengths of the windchimes. If you live in an area which receives less wind and need a larger windsail, we suggest trying one size larger than your current sail. Individual windsails are shipped via USPS (unless ordered with one of our other products). Replacement wind sails are sold individually for at-home installation. We do not replace stock sails on new chimes with alternate sails prior to shipping. Each size sail is intended for use with its original chime and not recommended for use on any other product.