Ice screw - A screw used to protect a climb over steep ice or for setting up a crevasse rescue system. The strongest and most reliable is the modern tubular ice screw which ranges in length from 13 to 23 cm. The approximate kN rating on a modern tubular ice screw is around 10kN. The older type of screw that is rarely used anymore is a pound in ice screw. Instead of screwing these into the rock you would pound them into the rock with the hammer on your ice tool. The pound ins have been largely replaced by "screw in" ice screws due to the screw in's ease of use.