Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 19957 found under Block by South Bay Redox Medical Supplies. The National Stock Number assigned to this part is 3610010645291, and the Federal Supply Class is 3610 Printing Duplicating And Bookbinding Equipment. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 19957.