A modern climbing rope, a key piece of safety equipment, is of kernmantle construction, consisting of continuous braided nylon fibers, the kern, surrounded by a continuous braided nylon outer sheath, the mantle. Such construction is superior to the more traditional laid rope (three large strands twisted together) because the outer sheath protects the inner core, where most of the strength lies, from the elements.
Climbing rope is dynamic: able to stretch a bit under tension. This is because the rope must stop falling climbers. If the rope did not stretch, a falling climber would be jerked suddenly as the rope stops him. Instead, the rope slows his fall more gently.
Climbing ropes are usually ten to eleven millimeters in diameter and fifty meters (about 165 feet) long. Such ropes cost between $100 and $180.
