Hex Flange Screws
A Serrated Hex Flange Screw is an unslotted hex head screw with a unified thread pitch and a flange that has serrations under the head or on the bearing surface side.
Serrated hex flange screws are 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. The flange provides more strength than a standard machine screw and eliminates the need for a lockwasher or locknut in certain applications.