Place your arms inside the main coil. Spin your arms, allowing the rope to un-wind. Always use a dynamic rope for lead climbing. Static ropes may be used for rappelling, rescuing, caving, top roping, and hauling where there is no chance of significant impact loading. Single ropes vary in diameter from 9.8 to 11 millimeters.
Thick ropes last longer and usually hold more falls.
Small diameter ropes are lighter and easier to clip into protection, making them the preferred choice for high-end lead climbing and glacier travel. Double ropes may be clipped alternately through the protection, reducing rope drag and decreasing the chances of rope failure over an edge. Both of the twin ropes are clipped through every protection point. The strands should never be separated. Twin ropes are uncommon in the United States.