Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 178-2489 found under Washerflat by Superior Washer And Gasket Corp. The National Stock Number assigned to this part is 5310016991021, 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 178-2489.