Review: Mammut Smart Alpine and Petzl GRIGRI + (belay devices)

The device does automatically lock off when weighted for lead and top rope belaying. Though this model is rated for ropes that are 8.7 to 10.5mm, I’ve found it to be jerky when the rope is 9.8mm or thicker, especially if its a well used rope. For top ropes it works great, just as well as a GRIGRI.