The ForgeFix Hexagon Bolt, Nut & Washer Kit contains a selection of the most popular sizes and is supplied in a handy ForgePack. Contains:

95 x ZP Round Head Machine Screws: 4.0x12mm(x20), 4.0x25mm(x18), 5.0x25mm(x18), 5.0x30mm(x12), 6.0x20mm(x12), 6.0x25mm(x9) and 6.0x30mm(x6).
95 x ZP Hex Nuts: 4mm(x38), 5mm(x30) and 6mm(x27).
95 x ZP Flat Washers: 4mm(x38), 5mm(x30) and 6mm(x27).