Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 556056-128 found under Resistor Variable Nonwire Wound by Singer Co The. The National Stock Number assigned to this part is 5905010331928, and the Federal Supply Class is 5905 Resistors. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 556056-128.