Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B42S4 found under Valve Ball by Whitey Co. The National Stock Number assigned to this part is 4820010351425, and the Federal Supply Class is 4820 Valves Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like B42S4.