Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 21CLM found under True Square by Ls Starrett Company The. The National Stock Number assigned to this part is 5220004791166, and the Federal Supply Class is 5220 Inspection Gages And Precision Layout Tools. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 21CLM.