The Jackson 20-330 Series Grade 1 Overhead Concealed Closer meets ANSI/BHMA Grade 1 Closer requirements. The closer is manufactured in the U.S.A. under strict ISO 9001 guidelines and is designed to give ultimate durability and maintenance free performance. This closer is truly universal. One basic closer mechanism allows for single or double acting, center-hung or offset applications and is non-handed. Suitable for both interior and exterior installations, it provides complete door control in a compact and concealed design suitable for aluminum, glass, wood and hollow metal doors.