Ski mountaineering is a sport of the skiing discipline which combines aspects of ski touring, backcountry skiing, Telemark, and mountaineering. The objective of the sport is to climb up a mountain wearing skis, and occasionally carrying them if the ascent is too steep, and then descend on skis after reaching a fixed point. It is practiced both at a recreational and competitive level, and is mostly popular in Europe. The skis used for the sport should not weigh more than four pounds, and are classified into two major types, free-heel Telemark skis and a variation of Alpine skis in which the heel is free for ascents and is fixed during descents. Bindings, light and flexible boots, and ski skins to walk upslope, are the other equipment required. Competitions are conducted on established trails on challenging alpine terrains, in which competitors are required to pass through a series of checkpoints. Races are mostly timed events in which the athlete to complete the ascent and descent in the fastest time is the winner. The three most important races in the sport of ski mountaineering are, the Mezzalama Trophy in Italy, the Patrouille des Glaciers in Switzerland, and the Pierra Menta in France.