Abstract: A vertical fall arrest device that combines, in a single unit, a fall arrest function, the capability to automatically traverse intermediate supports provided along a safety line and ease of attachment and detachment from the safety line at any point throughout the length of the safety line with dismantling the device. When the device is attached to the safety line, the safety line is captured in a retaining recess and is always in a ready state to lock-on to the safety line in the event of a fall condition. The device can be removed from the safety line easily and without disassembly by depressing a release catch while at the same time pulling a rotatable member a limited distance in a direction away from the main body. The rotatable member moves away from the main body against a spring bias and creates an opening for the withdrawal of the safety line from its captured position. When the pulling force is relaxed, the spring bias causes the rotatable member to relax to the fully locked position.