Wristlets are deployed when there is no other way to get a rescuer or victim out of a confined space. Most often this is because the entry is too narrow or restricted to allow retrieval with a regular harness and a D-ring attachment.
Wristlets must be used carefully because they can put so much strain on a persons joints and muscles. This can be painful and may cause injury, but in an emergency they can be an excellent rescue tool.
Wrist straps are also used for horizontal extraction. In some cases rescuers may be required to crawl into a very narrow pipe that would make their getting out difficult. These wristlets from DBI-SALA have sliding straps that are big enough to go over feet and shoes as well as wrists. With a line attached to wristlets on the rescuers' ankles, they can be dragged back out once their work is completed.