Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number OS-CAL 250+D found under Calcium Carbonate A by Sanofi Aventis Us Inc. The National Stock Number assigned to this part is 6505013398622, 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 OS-CAL 250+D.