I was hunting with my new Summit Viper last year and was coming down from my favorite tree. I had tied the upper and lower units with the supplied rope. The mistake I made was tying them the entire length of the rope (at the ends). The lower unit slipped while climbing down and I'm sitting on the outside rail with my feet locked around the tree, pulling the lower unit back up a long way. The lesson here is; don't leave too much rope between the upper/lower units.