Speed Skating can be practiced on covered or uncovered ice rinks, and often on artificial ice surfaces, but during Olympic events the rule these days is a covered oval track. According to regulations established by the ISU, a standard track must measure 400 or 333.33 meters in length, but generally speaking the first format is retained for major competitions. Each race is the departure of two competitors, each leaving from the point where two lines are drawn on the ice to ensure an equal travel distance. The goal is not to beat an opponent but rather to travel a given distance as quickly as possible. Each line has a colour, and in order to make skaters more easily identifiable and offer better visibility to spectators, a cuff of the same colour is worn by the respective skater (white inside, red outside). The common distances are 500m, 1,000m, 1,500m, 3,000m (for women only), 5,000m, and 10,000m. There are also team pursuit events, in which athletes wear transponders around each ankle.