Our 440T Trapped Key Solenoid Release Unit electrically isolates machinery to improve access safety. The unit consists of a rotary power switch and a solenoid. The trapped key can be removed once an external signal is given to its internal solenoid locking mechanism. An indicator light on the solenoid release unit shows when the trapped key can be removed—that is, when power is applied to the solenoid. The solenoid signal only needs to be present when key removal is necessary.