1. Size There are 10 sizes of screws: M2 * 4; M2 * 8; M2 * 6; M2.5 * 8; M2 * 10; M2.5 * 4; M2.5 * 6; M2.5 * 5; M2.5 * 8; M3 * 5; M3 * 4; 500 pieces in total. There are enough sizes and quantities to meet your daily and professional needs.2. Material Our screws are made of carbon steel, black zinc plating and flat thin head3. Application These mini screws are widely used to repair various brands of notebook or watch, jewelry and electronic products.4. Features The thread of the screw is deep, clean and clear, and the force is even. While rotating, it is easy to lock, not easy to slide, and easy to use.5. Package 500 pieces screws contain 10 sizes that are used in notebooks (each size 50 pieces). Each type of screw is in a separate grid which is very convenient for repairing yours.