The Carriage bolt, also called mushroom head square neck bolt or round head square neck bolts, the commonly used standrads are DIN603,Infly Fasteners Inc is a manufacturers factory of DIN603 metric Carriage Bolt, to supply to Mushroom head square neck bolt and Round head square neck bolt, we are according to DIN603 and EN ISO 898. About Carriage bolt DIN603, we can do: Size: diameter:M5-M16, Length: 20-200mm Material: Carbon steel class 4.8-8.8, Q195, 1008, 1035, 10B21 Surface: Self, colour, White zinc, Blue zinc, Yellow Zinc, Black, Hot dip galvanizing Packing: bulk about 20KG-25KG carton and then on pallet.