ABH 3500 Surface Mount 180˚ Parallel Arm HolderThe ABH 3500 Series is a heavy duty parallel arm holder for exterior, vestibule and interior single acting doors 24" to 36". Overhead holders are used to prevent unnecessary damage to the door, frame, wall and other door hardware by limiting the degree of door swing. They are installed at the top of a door opening; therefore, out of the general reach and not a tripping hazard. Whether for commercial or residential application, the use of overhead