They are also designed to work seamlessly with the Waterdrop Filter for WD-CTF-01 and WD-CTF-02 systems, and can be used as a perfect for the WD-CFF-01 filter. High-Quality Safe Material: The Countertop Filter System is made from 304 food-stainless steel, giving it a stylish brushed appearance and free from harmful substances like lead and BPA.