Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number R63870B18E6857 found under Cross Tube by Unifab Industries Inc. The National Stock Number assigned to this part is 4730007076946, 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 R63870B18E6857.