Installs easily on single and double ropes All clamping surfaces are smooth and won't damage the rope Can be used on single or doubles ropes to ascend Specifications: Meets CE Certification Compatibility with single 10-11 mm or double 8-11 mm ropes The Petzl Shunt Mechanical Prusik allows a piece of mind as a rappel back-up device. It replaces hitches like the Prusik and can be used on single and double ropes