Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 61-3900 found under Tube Metallic by Sea Tech Systems Inc. The National Stock Number assigned to this part is 4710013582449, and the Federal Supply Class is 4710 Pipe Tube And Rigid Tubing. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 61-3900.