Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 12399 found under Washer Spring Tensi by Laguna Pueblo Of. The National Stock Number assigned to this part is 5310000018165, 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 12399.