Forgefix flat mudguard washers zp forgefix 10mudwash850 these forgefix flat mudguard washers have a large 50mm outside diameter they are bright zinc plated for increased corrosion resistance washers provide a smooth surface for the nut or bolt to bear on making it less likely to loosen as a result of an uneven fastening surface the main purpose of a washer is to distribute the load under a bolt head or the nut face on all manner of bolting applications can be used with all types of bolt