Kohler. The company’s first one-piece, single-flush high-efficiency toilet, the Archer uses 1.28 gpf and includes Class 5 flushing technology, which features a 3 1/4-inch flush valve and an efficient, direct-fed jet to maximize water flow. The transitional design boasts beveled edges and a curved base. 800.456.4537. http://www.kohler.com/.