Light pulley suitable for the glacier

When hiking on a glacier it is appropriate to be equipped with a pulley as well, which will come in very handy during any rescue from a glacial crevasse. An effective solution is the use of a plastic roller, which you can thread onto an oval carabiner. The curve of the carabiner must be regular; this condition is met by figure eight carabiners or HMS carabiners. (Video from e-book Mountaineering Methodology, www.mountaineeringmethodology.com)