Competition rules for groups use rules made by or are an adjustment from rules by the International Ski Federation. For skiers with seeing problems, guides are used to help the skier down the mountain. For standing skiers, different part rules come to a decision about what sort of necessary things is let in competition, such as one long stick, two sticks or no sticks, or one or two skis. Seated skiers use a specially designed ski for going over snow quickly called a mono-ski. Skiers are put in a group based on medical, and their body position when they ski. Unable to see skiers are put in order only on a medical.