Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 2250-50-2 found under Antiserum Haemophil by Difco Laboratories. The National Stock Number assigned to this part is 6550008901951, 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 2250-50-2.