Chrome vanadium steel. Drop forged, heat treated with black finish. Sizes: 1/4"(M) - 3/8"(F), 3/8"(M) - 1/4"(F), 3/8"(M) - 1/2"(F), 1/2"(M) - 3/8"(F), 3/4"(M) - 1"(F), 1/2"(M) - 3/4"(F), 1"(M) - 3/4"(F), 3/4"(M) - 1/2"(F).