PETZL ASAP LOCK fall arrest Mobile fall arresters with fall arrest function for ropes. It automatically tracks every movement of the worker at height without any intervention. With its blocking function, the mobile fall arrester can be attached to the rope to reduce the potential fall height. In the event of a sudden movement caused by a fall, slip, uncontrolled descent, etc., it blocks the rope and stops the worker at height, even if he or she has a hand on the device.