A hex head screw with uniﬁed thread pitch and a ﬂange that has serrations on the bearing surface side.
Designed for use in applications where loosening forces are present,such as vibration. The serrations grip to the bearing surface so that signiﬁcantly more torque is needed to loosen than to tighten the screw. Flange provides more strength than a standard machine screw. Eliminates need for a lockwasher or locknut in certain applications.