Standard plain washers come in BZP, galvanised, stainless steel, and brass, in a wide range of sizes from M3 to M30. Where you need to spread a load over a wider area, penny washers have a larger diameter for a given hole size, these also come in a range of materials and sizes. Shake-proof washers have serrations either internally or externally to stop bolts coming undone where they are subject to vibration. There are also spring, or split-ring washers in a variety of sizes and materials. Nylon and rubber washers, including anti-vibration washers, square plate washers in a range of sizes, and bonded washers complete the range.