Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number D-2656-1 AND 2 found under Freeze Seal Unit by Harris Environmental Systems Inc. The National Stock Number assigned to this part is 4470011851913, and the Federal Supply Class is . Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like D-2656-1 AND 2.