The absolute classic design from Black Diamond that is perfect for all belaying & abseiling duties. The ATC (Air Traffic Controller) has a large heat dissipating surface area that protects it from over heating during long abseils or lowers. Smooth internal geometry handles ropes from 7.7 mm to 11 mm & a good stiff keeper wire stops it from getting jammed up in your belay carabiner. Minimalist, easy-to-use design is well suited for a wide variety of climbing situations Large surface area dissipates heat while lowering or rappelling Durable cable holds its shape & resists getting caught between ropes Hot-forged construction Handles ropes from 7.7 mm to 11 mm