Arm code A, arm shock mount, 3mm screw, flat washer, aluminum alloy material Inner diameter 3.0mm Outer diameter 5.8mm 6 thicknesses: 0.5/1.0/1.5/2.0/2.5/3.0, Each thickness has 4 pieces, totaling 24 pieces. Used for adjusting the gap of 3mm screw positions for arm codes or A-arms, shock mounts, etc