Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 3IL31 4200 18500 0 0 found under Filter Low Pass by K And L Microwave Inc. The National Stock Number assigned to this part is 5915013444630, and the Federal Supply Class is 5915 Filters And Networks. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 3IL31 4200 18500 0 0.