Hex Flange Screws
Click image to enlarge
Flange screws also known as serrated hex washer head flange screws or flange bolts have a washer type flange attached to the hex head which is usually serrated under the washer closest to the threads. Serrated Hex Washer Flange screws a/k/a Serrated Flange bolts are a one-piece bolt or screw with a hex washer head and serrated flange under the hex washer head and are zinc plated ZP steel.