Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 663C7559 ITEM 20 found under Filter Element Flui by Aqua Chem Inc. The National Stock Number assigned to this part is 4620012640712, and the Federal Supply Class is 4620 Water Distillation Equipment Marine And Industrial. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 663C7559 ITEM 20.