These cap head hex socket screws are made of 12.9 grade alloy steel with oxidation surface, which are resistant to rust and corrosion. There are 9 thread lengths for you to choose from, which can be generally used in home and office appliance, machinery, furniture, etc. Features: 1. 12.9 grade alloy steel material with oxidation surface has good strength of extension and corrosion resistance in many environments. 2. Cap head enables driving where it doesn't have sufficient space for wrenches. 3. Ideal for use in confined areas where the head needs to be flush or below the surface. 4. Used for fasteners in home and office appliance, communication equipment, ship assembly or other machinery industry. 5. Screws and nuts are well packed in 10 compartments and assorted in a transparent plastic box for convenient use and storage. Specifications: Material: 12.9 Grade Alloy Steel Color: Black Screw Thread Lengths: 4mm(20Pcs), 5mm(20Pcs), 6mm(20Pcs), 8mm(20Pcs), 10mm(20Pcs), 12mm(20Pcs), 16mm(20Pcs), 20mm(20Pcs), 25mm(20Pcs) Thread Diameter: 3mm (M3) Box Size: 13 * 6.5 * 2.3cm / 5 * 2.6 * 0.9inch Quantity: 1 x Box of 180Pcs Screws + 100Pcs Nuts Package Weight: 228g Type: Cap Head Hex Socket Screw Function: Fastener Package Includes: 180 x Screws 100 x Nuts Note: 934 on the box lable is abbreviated from DIN934, which means cap head hex socket nut. The length of the screw does not include the thickness of the head of the screw.The thickness of the screw head is 2.95mm.