Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number FIG NO. 4211 ITEM NO. 15 found under O Ring by Zidell Valve Corp. The National Stock Number assigned to this part is 5331014407705, 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 FIG NO. 4211 ITEM NO. 15.