Carbon steel Hex Cap Bolt set, better know as Allen Bolts or Hex Bolts. 106 bolts in total with a handy storage case. Carbon Steel. Black Finish. 106 pieces in metric sizes (mm): 25pc 4x12, 25pc 5x12, 20pc 5x25, 10pc 6x12, 10pc 6x25, 5pc 8x25, 5pc 8x40, 3pc 10x25, 3pc 10x40. Head Diameter (mm): M4 = 6.5, M5 = 7.6, M6= 9.3, M8 = 11.3, M10 = 13.6. Brand: Toolzone. .