For both work-at-height and rescue, access from above is preferable because it allows one to take advantage of the force of gravity to save energy. Descenders are designed to help regulate friction and control the descent on a fixed rope. They allow a worker to position himself at any point on the rope. Some descenders can also be used to belay a leader using lead climbing techniques.
Mechanical Prusik for tree care
Personal escape systems
Personal escape system with anchor hook adapted for locations where the possibility of finding an ...