Metallics JG5HSF381 Bolt 3/8-16 x 1 Ind Hx Hd Serr Flan (Jar 100)

That's the point of the design. The serrated flange under the hex head spreads the bearing load like an integral washer and the serrations bite into the mating surface to resist loosening from vibration, so the JG5HSF381 is typically run without a separate flat or lock washer. Keep in mind the serrations mar the surface they clamp against, so it's not the fastener for a finished or painted face you need to keep intact.

100 pieces, packed in a jar. The jar is a shop-counter pack, so it's sized for strut channel, panel, and enclosure work where you're pulling fasteners one at a time rather than opening a bulk box.

Order Metallics JG5HSF381. That number covers the 3/8-16 x 1 inch indented hex head serrated flange bolt in the 100-piece jar, and it's the only configuration that number carries, so there's no size or finish suffix to add.

It's a common pick for it. Metallics catalogs the JG5HSF381 as an electrical fastener, and the serrated flange head is what electricians reach for on channel, bracket, and enclosure connections where vibration would back a plain hex bolt out. Where you need the fastener to pull through an unthreaded hole, pair it with a 3/8-16 flange nut; where the hole is tapped 3/8-16, the bolt alone does the job. For sheet metal too thin to carry a 3/8 bolt, a self-drilling screw or smaller machine screw is the better fastener.