Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 681R556H01 found under Printed Circuit Board by Circuits Inc. The National Stock Number assigned to this part is 5998013323090, and the Federal Supply Class is 5998 Electrical And Electronic Assemblies Boards Cards And Associated Hardware. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 681R556H01.