Chicago screws also known as binding screws, book screws includes 6 sizes: 20 sets M5x4mm, 25 sets M5x5mm, 20 sets M5x6mm, 15 sets M5x8mm, 15 sets M5x10mm, 15 sets M5x12mm, 1 x screwdriver; 1 x hit. Intotal 110 sets, enough to meet your daily needs. Which makes your DIY work more beautiful. High-quality Chicago binding screws made of carbon steel, Make it heavy for long-lasting results.The surface is plated to make it smooth and burr-free, wear-resistant, rust-resistant, reusable. All rivets are stored in a transparent and sturdy storage box with compartments with different screw post sizes. Leather rivets are stored separately, easy to carry and find. It also prevents screws from being lost when not in use. These leather rivets are very easy to install. Insert the bolt through the hole, align the nut with the bolt and tighten the screw. The screw rivets are completely flat on the bottom and will not hook during assembly. Gunmetal black Chicago screws are well suited for leather crafts such as belts, bags and shoes - a must-have for all DIY fans! This set of screw rivets will meet your needs. Color: Material:Metal Package Contents: 1set * rivets for leather crafting Note: Please allow 1-3 mm error/1-83g weight error and actual product color may vary due to lighting conditions.