Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 37-4X1-8-20A5 found under O Ring by Victoria Technologies. The National Stock Number assigned to this part is 5331143743489, and the Federal Supply Class is . Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 37-4X1-8-20A5.