10-16X1 1/4 Slotted Indent Hex Washer Serrated Self Tap Screw Type AB Full Thread Zinc (Pack Qty 3,000) BC-1020ABSWS

The serrations on the underside of the washer face allow this part to perform two main functions: (1) act as a locking fastener, and (2) break drive torque during installation which lessens the chance of reaming out the mating hole in the bearing surface. The torque-breaking feature slows the rotation of the screw when it meets the mating surface. The serrations allow for more pitch body diameter under the head giving the mating sheet metal more travel so as not to snap over the last bit of major diameter thread crest. AISI 1016 - 1024 or equivalent steel