Brass Flat washers are used under bolt heads or nuts to increase the bearing surface area, or to offer protection so that the nut or bolt can be rotated without distortion of the bearing surface. Flat washers are also used to give tightness to a joint, to prevent leakage, and especially to distribute pressure under the head of a bolt or nut. Brass fasteners are commonly used by electrical and communications industries, builders hardware and some marine applications. These washers provide corrosion resistance in wet environments, offer thermal and electrical conductivity, and are nonmagnetic.