Material: Alloy Q'ty: 4 pieces Outer diameter:1.4 x 0.82''(35 x 21 cm), inner diameter:1 x 0.47''(25 x 12 cm).Thickness:approx: 0.2" (7 mm) Easy to operate with the built-in spring, quick connect and release, very convenient to use. Can be used to attach to the backpack, handbag, or use as a keyring, dog leash for daily life. And used to hang crafts or decorations to anywhere you want. You can get black gun 4 pieces,it's perfect for your crafts.