KT Foiling Shim KitIncludes all positive, negative and 0 degrees shims. 12 shims : From 3 degrees to 2. 5 degrees. 1. You have to use a Tail Shim. Without the use of the recommended tail shim between the back wing and the fuselage, the glide and performance of your KT Foil will be compromised. Only use shims provided by KT Foiling. 2. Front Wing Value + Mast Value = Tail Shim Value. The sum of the Front Wing value (printed on product) and Mast value (printed on product)