Gr.5 Large Serrated Hex Flange Machine Bolts: This bolt features a large integrated flange with serrations under the head as well as a fully threaded shank. Available with a trivalent (rohs) finish, sizes range from 1/4" ~ 3/8" diameters. [A non-indented head is recommended as it prevents grease and dirt from accumulating on the head while providing a higher quality finish and appearance.]