UNC ZINC PLATED STEEL 12.9 HIGH TENSILE STEEL SOCKET CAP ALLEN BOLTS. UNC (Imperial coarse thread). Zinc plated. 12.9 grade high tensile steel. 3/8" - 16 tpi. 5/16" - 18 tpi. 1/4 - 20 tpi. 3/16 - 24 tpi (10-24).
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