Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number WS-20BB found under Cartridge Water Dem by Pentair Filtration Inc. The National Stock Number assigned to this part is 4610016009459, and the Federal Supply Class is 4610 Water Purification Equipment. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like WS-20BB.