The Norton Rixson 993M Electromagnetic Door Holder offers a powerful 300 lbs holding force, ensuring secure door positioning. It features a total projection of 5-1/4" (133 mm), suitable for various mounting needs, either surface or concealed. The included switch box measures 4-1/2" x 4-9/16" x 2-1/2" (114 x 116 x 64 mm) deep for easy installation. The armature plate is through-bolted to maintain consistent contact with the magnet, with an adjustable screw on a heavy-duty armature for precise alignment. The unit includes a test switch but is also available without one for frequent door releases. A key switch (by others) allows manual release. Note that substantial wall reinforcement is necessary. Enhance your door management with this reliable and adjustable door holder today.