There are several systems in use to grade mountain climbs. Alpine mountaineering routes are usually graded based on all of their different aspects, as they can be very diverse. Thus, a mountain route may be graded 5.6 (rock difficulty), A2 (aid difficulty), WI3 (ice climbing difficulty), M5 * (mixed climbing difficulty), 70 degrees (steepness), 4000 ft (length), VI (commitment level), and many other factors. See also Summitpost Alpine Grades.