Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number R3840A found under Wrench Ratchet by Snap On Tools Corp. The National Stock Number assigned to this part is 5120015844487, 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 R3840A.