Install Lifeline Plus in tree the first time you climb. Allows for two people to remain attached to the same lifeline line includes 2 prussic knots and 2 carabineers. Ascend in the tree and provides 100% protection against falls on any future trips up the tree. Clip your tether into the carabineer attached to the rope and slide the Prussic knot up the rope as you climb. Any fall results in the tightening of the unique knot and stops your fall.