The KOHLER Highline toilet tank features innovative Revolution 360® technology, an advanced flushing system that uses a powerful swirling motion to thoroughly rinse the bowl. This water-efficient toilet tank also utilizes innovative AquaPiston® technology, a patented flush engine that delivers a fast, powerful, and virtually plug-free flush. A 1.28-gallon flush provides significant water savings of up to 16,500 gallons per year, compared to a 3.5-gallon toilet, without sacrificing performance.