300 pieces - This carbon steel screw and washer set includes M3 socket head cap screws in size of M3 x 4mm,5mm,6mm,8mm,10mm,12mm,25 pieces each. Comes with M3 carbon steel hex nut,flat washer and spring washer,50 pieces each.^Socket Head - Socket Hex Socket Head Cap Screws are easy and convenient to assemble and disassemble with internal hex key. It has relatively large clamping force and more beautiful and neat.^Material - These black pan head hex head bolts and screws are made of carbon steel,which has high hardness and better wear resistance. The surface of these fasteners is blackened by oxidation to prevent rusting.^Comes with a storage box - Comes with a clear plastic box with 9 separate compartments for easy storage and transport. So they will not be mixed up or missing. No need to worry about small screws which will be hard to find in your toolbox.^Wide Applications - Alloy steel pan head screws can be used as fasteners in machines,designs or structures with relatively smooth surfaces and high precision requirements. Good for home and office appliances,furniture,ships or other machinery industries.