NS3 skiers' vision is constricted to a diameter of less than sixty degrees and/or they have the ability to detect a tennis ball sized object at a maximum distance of three metres. They can opt to use a guide who skis in front of the athlete giving verbal directions around the course.
Generally, visually impaired cross-country skiers all race together as NS1-3 using a factored timing system, which alters the running speed of the clock.