The Wafer-Sphere(r) butterfly valve from Jamesbury, Inc. (Worcester, MA) features the Xtreme(tm) seat, which is designed to provide longer life and expanded performance boundaries of up to 350 psi at 500 degrees, according to the manufacturer. Other features include self-lubricating or fiberglass-backed TFE shaft bearings, availability in a wide range of materials for specific chemical media, and a range of ANSI pressure classes: 150, 300, and 600 lb.