These forgefix screw cup washers are made from solid brass with a nickel plated finish to avoid corrosion they are quick and easy to install with no need to countersink screws application to enable flush finish in numerous joinery installations can be used with most screw types the nickel plating process provides a coating to considerably prolong the parts life nickel plating is probably the most corrosion resistant finish available and is often used on socket screws for electric switch sockets