Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 6401 3F found under Marker Tube Type by Koh I Noor Rapidograph Inc. The National Stock Number assigned to this part is 7520013397434, and the Federal Supply Class is . Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 6401 3F.