The Petzl Ascension Ascender features a simple and ergonomic design for comfort and ease of use.. . . . . Ergonomic molded handle is easy to grab with wide opening allows for a comfortable and powerful grip with or without gloves. Upper allows for pulling with two hands. Safety catch is integrated into ascenders body to prevent snagging . Toothed cam with self cleaning slot provide optimal performance on dirty,wet, and icy ropes. Wide lower hole has enough room to accommodate multiple carabiners. Upper hole for clipping a carabiner around the rope . For use with ropes between 8 13 mm .