Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 537628-20 found under Washer Flat by Raytheon Company. The National Stock Number assigned to this part is 5310007633413, and the Federal Supply Class is 5310 Nuts And Washers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 537628-20.