Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number X143-20MHZ found under Oscillator Crystal Controlled by Xsis Electronics Inc. The National Stock Number assigned to this part is 5955010471755, 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 X143-20MHZ.