Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number V21-BBU found under Battery Backup by Emc Corp. The National Stock Number assigned to this part is 6130016432139, and the Federal Supply Class is 6130 Converters Electrical Non Rotating. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like V21-BBU.