This British Standard specifies the materials, dimensions and finish of mild steel, corrosion-resisting steel and aluminium alloy washers suitable for use with bolts with Unified hexagons for aircraft. The washers are intended primarily for use for packing purposes.

Provision has been made for oversize bore washers for use when used in conjunction with oversize plain shank bolts, with the oversize washer being fitted onto the bolt head side of the clamped joint.