500 series. Size 3 spring. Grade 3 door closer fits 3' interior doors and 2' 6" exterior doors. It has a regular parallel arm and top jamb mount. It is made from non-handed, cast aluminum. The door range is up to 180 . It has an adjustablesweep and latch. It is UL listed. the retro fits traditional closer 9-1/6" horizontal and 3/4" vertical mounting holes.