Sun Xtender® batteries are engineered specifically for renewable energy and solar applications. All Sun Xtender® batteries are hand built in the U.S.A. with higher density plate technology that provides superior reliability and power in renewable energy's deep cycle environments. Although Sun Xtender® batteries are engineered to perform under the conditions dictated by solar and renewable energy applications each battery is built to the same quality aircraft standards as the renowned Concorde Aircraft battery line under ISO 9001:2008 + AS9100 (Aerospace) Quality Management System.