Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 1661-1IN found under Tee Pipe by Ati Ladish Llc. The National Stock Number assigned to this part is 4730012771381, and the Federal Supply Class is 4730 Hose Pipe Tube Lubrication And Railing Fittings. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 1661-1IN.