... of washer High Quality Combination Screw 1. Head type of Combination Screw:ASTM/JIS pan head,hex head,.high round ... With double washer,flat and split washer with three washer4. Material of Combination Screw:Carbon steel, Alloy steel ... phosphate black, 3Cr zinc,Passivation8. Packing of Combination Screw:General packing: 15-20Kg per Carbon or Bag, ... 7mm 7mm 8mm 12mm 15mm High Quality Combination Screw