M4 Form A Flat Washer DIN125A Brass

This is a plain narrow flat brass washers form A which denotes the outside diameter of the flat washers The washers are DIN 125A standard which are used to spead the load when tightening fasteners so the nuts and bolts have a good contact surface to assist in keeping the nut or bolt secure.  Washers also take the pressure from just a small space by spreading the load from the component side to prevent wear in the connection of the fastening.

These are brass fasteners which is a preventative measure from corrosion and used for electrical fixings or for decorative applications.  Bear in mind using different materials can cause fusing through corrosion especially in damp conditions when mixed with aluminium or stainless steel materials.

More information is available from Central Fasteners regarding fastener details, but its always worth checking with a manufacturer's specifications or drawings if an alternative size, tensile strength or types of washers are used.