10.9 Alloy Steel: Class 10.9 Steel are considered hardened, providing a high strength, high tensile fastening solution, coated with zinc black provides better rust resistance, won't strip easily.
Flange Design: There have a flange on the bottom of the bolts head, which distributes the load like a washer; And serred flange make it screw firmly. Flanged Bolts are great to have around for use in wood and wet environments.