The first necessary things used in the sport includes outrigger skis, sit-skis, and mono-skis. Being dependent on if a skier sits, stands or cannot see, other necessary things may be used by skiers other equipment may be used by skiers including guide skiers, short ski poles, orthopedic aids, or prostheses. For skiers with seeing problems, guides are used to help the skier know the direction to ski. [10] For skiers who stand. Different part rules decide what sort of necessary things is let in competition, such as one long ski pole, two ski poles, zero ski poles, or one or two skis. Rules for necessary things use in competition are made by FIS and the IPC.