Peco Lag Bolt, Measurement System: Imperial, 1/4-10 Thread, 2-1/2 in Overall Length, Steel, Zinc Plated, Gimlet Point, 0.15 to 0.188 in H x 0.484 to 0.505 in W Head, 0.237 to 0.26 in Shoulder Diameter, 0.094 in Shoulder Length, Rockwell B70 to B100 Hardness, Hex Head