Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number FC66A found under Crowfoot Attachment Socket Wrenc by Snap On Tools Corp. The National Stock Number assigned to this part is 5120013351148, and the Federal Supply Class is 5120 Hand Tools Nonedged Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like FC66A.