Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 643-0003 found under Horn Loudspeaker by Wisconsin Oven Corporation. The National Stock Number assigned to this part is 5965015360016, and the Federal Supply Class is 5965 Headsets Handsets Microphones And Speakers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 643-0003.