Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number HS-509-50MHZ found under Oscillator Crystal by Nel Frequency Controls Inc. The National Stock Number assigned to this part is 5955013818140, 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 HS-509-50MHZ.