Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 6643SDB-2 found under Delay Line by Damon Corp Electronics Div. The National Stock Number assigned to this part is 5999001310005, and the Federal Supply Class is 5999 Miscellaneous Electrical And Electronic Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 6643SDB-2.