Zurn's ZERK products work well in all bathroom environments adapting to various water pressures and water quality. They are equipped with special features like user-in view L.E.D, low battery indicator light, switchable 24 hour auto flush and three second delay flush to deter false flushing, 10 degree angled sensor for optimum user detection, courtesy flush button with high impact resistant polycarbonate, housing impact-resistant glass lens, chrome-plated metal cover, 4 C-size batteries, wrench for installation and allen key for the battery compartment. ZERK CPM directs the water from the lower valve chamber through a plurality of individual passageways and into one of the twenty-two filter cells around the diaphragm giving you filtered clean water.