Washers – Heavy-Duty C-Washer, Steel Made from cold finished steel and then case hardened. Black oxide finish. Machined flat and parallel with no sharp edges., Inch S&W P/N Slot Width (A) Thickness (B) Outside Dia (C) MW-3 9/32 1/4 1 1/4 MW-7 11/32 5/16 1 1/4 MW-12 13/32 3/8 1 1/2 MW-18 17/32 3/8 2 MW-21 21/32 3/8 2 1/8 MW-24 25/32 7/16 2 1/2 MW-27 29/32 1/2 2 5/8 MW-29 1 1/32 9/16 3