Duro (15641) heavy-duty commercial door closer. Performance: ANSI A156.4, Grade 1. (2 millions cycles). UL listed. Nonhanded, cast aluminum, mounting to regular, top jamb or parallel arm applications. Adjustable sizes 1 to 4. Adjustable hydraulic backcheck provides cushioning and prevents uncontrolled openings at the door. Door prep: 9-1/16'' horizontal and 3/4'' vertical mounting hole locations.