This design has been offered because of the extra security. The ring can be closed fast and easily attached to the birds leg by pinching the sides together. Once the ring is closed, it can not be opened unless you want to open it by using something with a point, such as a pen. No more finding bands on the floor when the pigeon somehow manages to get it off. Bands are sold in size 7mm and 8mm, 7mm fits Rollers, Tippler and many more breeds. Size 8mm fits Racing Homers, Chinese Owls, Jacobins and many more. Packed 12 per container. E-Z Lockrings: Size 8, Numbered BLACK 1 - 12