Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 0561B0028-1 found under Seal Plain Encased by Martin Marietta Technologies Inc. The National Stock Number assigned to this part is 5330010961266, and the Federal Supply Class is 5330 Packing And Gasket Materials. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 0561B0028-1.