Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 4091-18 found under Fixture Indicator Concentricity by Crafts Precision Industreis Inc. The National Stock Number assigned to this part is 3465011264890, and the Federal Supply Class is 3465 Production Jigs Fixtures And Template. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 4091-18.