Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 50554 found under Caliper Set Micrometer Inside by Ls Starrett Company The. The National Stock Number assigned to this part is 5210003307622, and the Federal Supply Class is 5210 Measuring Tools Craftsmens. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 50554.