Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 4S6399 found under Adapter Straight Pipe To Tube by Caterpillar Inc. The National Stock Number assigned to this part is 4730011275373, 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 4S6399.