HIGH QUALITY: Made of high quality brass, sturdy and durable, neck width: 6mm; Thread diameter: 3mm, sturdy, high hardness SMOOTH APPEARANCE: Overall surface appearance, smooth, burr-free, strong and durable. Can be used for album or book and other binding books HOW TO USE: Fasten, the wire is clean and clear, they can be inserted after assembly by knocking them down into the slot, inserting a nut into the slot and twisting them with a screw locking the nut in place WIDE APPLICATION: These mini double cap rivets are perfect for your super lightweight projects, suitable for luggage, home textiles, shoes, hats, pants, bras, jackets, pet collars, belts, etc. 3 SIZES TO CHOOSE: Package include Quantity: 10 sets, 3 sizes for your choice, easy to use and clean, enough for your normal use