Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number D5100U found under Mixer Crystal Waveguide by Watkins Johnson Intl. The National Stock Number assigned to this part is 5985011023070, and the Federal Supply Class is 5985 Antennas Waveguides And Related Equipment. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like D5100U.