This Aluminum spacer can be widely used in high-temperature, high-pressure, and highly corrosive pressure, valves, sealing parts of cylinder heads, and industries such as steel mills, chemical equipment, and engineering machinery. Specification Color: SilverMaterial: AluminumFit Screw Bolts Size: M4Size: 4.2 x 8 x 2 mm / 0.17 x 0.31 x 0.08 inch (ID*OD*L)Packing List: 10 x Round Aluminum SpacerAdvantageMade of durable Aluminum material, which is hard, good performance, good electrical conductivity, corrosion resistance and can be used for a long time.Instruction Easy to use, just need to install on the screw bolts with proper diameter.NOTE: Please select the appropriate size according to your needs.