A true variable-friction device, the ATC-XP maintains the silky-smooth feeding of the ATC but ups the braking power. For belaying and rappelling with 7.7-11 mm ropes, it’s designed with a smooth, low-friction side and a high-friction side with v-shaped grooves for three times more friction. An extended central web keeps biners and ropes properly oriented and helps reduce kinking. Black Diamond - ATC XP A true variable friction device the ATC XP maintains the silky smooth feeding of the ATC but ups the braking power For belaying and rappelling with 7 7 11 mm ropes it s designed with a smooth low friction side and a high friction side with v shaped grooves for three times more friction An extended central web keeps biners and ropes properly oriented and helps reduce kinking