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. This set of flat washers are made of high quality 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 looking for washers for quite a while. Material: Copper Color: 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 Package Contents: 280 x copper washers 1 x plastic box Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.