The Deligo IBW4 is a 100 pack of brass M4 round flat washer that is commonly used to spread the tension load of the material you are fixing to, so that you can create a strong hold that is not likely to loosen over time.These washers reduce maintenance work by allowing the loosening and tightening of components more smoothly. Suitable for many electrical installations. Manufactured from solid brass to DIN 125 and BS4320B standards for washers, they fit M4 bolts and screws. Can sometimes be referred to as penny washers, repair washers or fender washers. The Deligo IBW4 is a brass M4 round flat washer that is commonly used to spread the tension load of the material you are fixing to, so that you can create a strong hold that is not likely to loosen over time.. These self coloured Washers are manufactured from Brass which helps prevent corrosion with DIN standard 125