Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 18231 found under Spring Expander Piston Ring by Cadillac Gage Textron Inc. The National Stock Number assigned to this part is 2810016689943, and the Federal Supply Class is 2810 Gasoline Reciprocating Engines Aircraft Prime Mover And Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 18231.