Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 447328-B21 found under Disk Drive Unit by Hewlett Packard Co. The National Stock Number assigned to this part is 7025015964729, and the Federal Supply Class is 7025 Adp Input Output And Storage Devices. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 447328-B21.