Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number EXTERNAL STD NO. 2 found under Reference Standard Chloride And Total Carbon Dioxi by Nova Biomedical Corp. The National Stock Number assigned to this part is 6550011656725, 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 EXTERNAL STD NO. 2.