PETZL Verso Belay/Rappel Device 2" high 6" wide Asymmetrical V-shaped grooved friction channels adapt the friction for better control. Channels decrease friction when taking in slack for greater ease of use. The Verso can be used on all types of ropes: single (8.9mm and up), half (8mm and up) and twin (7.5mm and up). Used with a symmetrical locking carabiner.