Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number U18-20-60 found under by Foremost Machinery Corp. The National Stock Number assigned to this part is 5955013159899, and the Federal Supply Class is 5955 Oscillators And Piezoelectric Crystals. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like U18-20-60.