280pcs 12 Sizes Copper Flat Washer Plain Washers With Box Fitting for Screws Bolts Fasteners Description: The washer is a thin disk-shaped plate with a hole in the middle that is normally used to distribute the load of a threaded fastener, such as a screw or nut. Other uses are as a spacer, wear pad, pre-load indicating device, locking device, and to reduce vibration. High-quality bolted joints require hardened steel washers to prevent the loss of pre-load after the torque is applied. Washers are also important for preventing galvanic corrosion, particularly by insulating steel screws from aluminum surfaces. Features: This set of flat washers are made of copper of good electrical conductivity and thermal conductivity. Flat washers can spread a load, and prevent damage to the surface being fixed, and insulate steel screws from surface. Can be used as a spacer, wear pad, pre-load indicating device, locking device, and to reduce vibration. Flat washer is applied when the hole is a larger diameter than the fixing nut. There are many different sizes of washers in this set from which you can use for different purposes. This set includes many flat washers that can be used for a long time, so you don't have to run to hardware store looking for washers for quite a while. Specifications: Material: Copper Type: Flat washer ID*OD*Thickness & Quantity: M5*9*1mm          30pcs M6*10*1mm        30pcs M6*12*1mm        20pcs M8*12*1mm        30pcs M10*14*1mm      30pcs M8*14*1mm        20pcs M12*16*1mm      25pcs M14*18*1mm      25pcs M12*18*1.5mm   20pcs M16*20*1.5mm   20pcs M16*22*1.5mm   15pcs M20*26*1.5mm   15pcs Box Size: 17.5 x 10 x 2.3cm / 6.89 x 3.93 x 0.9" Package Includes: 1 set x Washers