Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 666587 4 found under Ink Tube Pen by Lds Test And Measurement Llc. The National Stock Number assigned to this part is 4720011401014, and the Federal Supply Class is 4720 Hose And Flexible Tubing. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 666587 4.