Not only does the Petzl Reverso 4 Belay and Rappel Device give you serious stopping power when you're holding massive whippers, but it also functions as an auto locking device when you're belaying the following climber directly off the anchor. This allows you to re rack, tie your shoes, sip some water, and take a few photos without risking your climbing partner's life. Belaying two followers at once' No problem. Rappelling 15 pitches' The deep grooves give you plenty of control. Petzl also added a secondary clip in point to help you release a locked rope if you need to lower a follower who has fallen.