Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 53778 found under Wrench Packing Nut by Hydro Test Products Inc. The National Stock Number assigned to this part is 5120012064928, 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 53778.