This is an essential item to prevent twisting and kinking of your wing's hand leash! (Especially since the loop cord on the wing itself cannot be replaced due to deterioration, preventing twists is the key to making your wing last longer.) How to use it: Simply insert it between the wing body and the leash cord. → ① Relieves hand stress caused by leash twisting & ② Prevents leash breakage due to accumulated twisting! The swivel weighs only 13g (No impact on weight-sensitive wings!) Made of rust-resistant brass, Tensile strength is 200kg (according to the manufacturer), Size is 10 x 34mm, with a 6mm inner hole diameter. Two high-strength 4mm black cords are included per set, but you can customize them to your liking. ★ Multiple sets are also available. (Set prices) 2 sets for 1500 yen 3 sets for 2100 yen → If you want multiple sets, please comment beforehand. (I will change the display and price.) Since this is a personal sale, I cannot guarantee performance, but I have been using it for 3 years without replacement. There is no breakage, deformation, rust, or sticking, and the stress of tangling in your hand during turns is greatly reduced.