Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 221MBK-SIZE 10 found under Boots Divers by Otb Footwear Llc. The National Stock Number assigned to this part is 4220016002143, and the Federal Supply Class is 4220 Marine Lifesaving And Diving Equipment. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 221MBK-SIZE 10.