This left-hand wound commercial spring failure device is designed to help prevent uncontrolled door movement if a torsion spring breaks. It is compatible with 1-3/4”, 2”, 2-5/8”, 3-3/4”, and 6” spring fittings and is intended for use with a 1” keyed solid shaft, with a 1-1/4” option available. It is not designed for duplex spring systems. One device is required per spring. The unit uses a 3-3/8” shaft offset, with an optional extension bracket available, and includes a mounting location for a limit switch. Maximum capacity is 1,850 lbs. per device. Sold individually.