For use with K-18829-NA 2-inx4-in in-wall tank and carrier system Large flush actuator plate opening can be removed for easy access to inner tank Dual flush actuator offers a choice of 0. 8 or 1. 6 gallons per flush (gpf) Water Sense toilets meet strict EPA flushing guidelines, including using at least 20 percent less water than 1. 6-gallon toilets