I checked out my set of BDL screws against a 1/4-20 flat head screw and the angle looked to be the same 82 degree taper but like it was mentioned before it has a lower profile and smaller diameter. The BDL head was about 1/8" tall and about 3/8" in diameter whereas the 1/4-20 was a half inch in diameter and slightly taller, about 3/16" I'd say.