Description Ideal as a back-up while on rappel, we constructed our Auto Block from a durable 6 mm cord sewn into a 13.5-inch loop. The Auto Block attaches from the harness to the brake-hand end of the rappel rope just below the rappel device and works as a prusik or with a Klemheist knot. *Please note that some descenders cannot be backed up below the device. Be sure to fully read and understand the instructions provided with your descender.*
