Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number CY 2857 U found under Case Crystal Unit S by Joint Electronics Type Designation. The National Stock Number assigned to this part is 5955007364654, 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 CY 2857 U.