The Allied Bolt Flat Washer (vendor part 314101, Millennium part 536691) is a 3/8 in Type 304 stainless steel washer supplied 4,000 pieces per carton for high-volume pole line and hardware installs. It seats under stainless bolt and screw heads to spread load and keep fasteners from working loose on outdoor structures exposed to weathering. The bulk carton format suits crews stocking trucks for repetitive aerial hardware runs rather than one-off jobs. Order it with matching stainless lag screws and hex bolts from Millennium for a complete corrosion-resistant fastening kit.