The Stanley Hardware 4-1/2-inch square corner Spring hinge is ideal for use in corridors, entrances and stairways. Supporting doors up to 4-by-8-feet, and weighing up to 180 pounds, this hinge is an alternative to overhead mounted door closers, as it automatically closes doors. A patented ratchet adjustment eliminates the need for an adjustment locking pin. This ratchet design allows for quick fine tuning tension up or down with the included allen hex key. Meeting the NFPA80 Standard for 3-hour fire-rated doors and the UK fire approval for use on FD30/FD60 doors, this hinge is also guaranteed with a lifetime warranty against defects in material and workmanship.