Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number BLK41 found under Filter Block by Dunham Bush Ltd. The National Stock Number assigned to this part is 2940011330322, and the Federal Supply Class is 2940 Engine Air And Oil Filters Strainers And Cleaners Nonaircraft. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like BLK41.