Penny Washers - Metric

M4 x 20mm - Repair Penny Washer - A2 Stainless Steel - Pack of 50

Often called repair washers or mudguard washers, penny washers have an overall outside diameter that is larger than standard flat washers.

This increased surface area spreads the force (and hence the tension load) that is applied over a much greater area when the nut is tightened, making them ideal for use on weak or damaged surfaces.

Metric is the most common thread type in production today. Usually specified as M then a number x another number. This signifies the thread diameter and the length of the fastener.

For example M4 x 30 means that the major thread diameter (the external distance across the outside of the thread) is 4mm and the length is 30mm. Length is usually measured from the underside of the fastener head.