sprint events have shorter courses with an expected winning time of 15 minutes and use either a 1:5000 or 1:4000 map. they use lower powered transmitters on the eighty metre band which transmit in sequence for only 12 secs with the cycle repeating every minute. the iaru region 1 rules require 2 sets of 5 transmitters where each set operates on a different frequency. the morse code transmitted by the second set of transmitters is slightly faster (paris 70) than the first set (paris 50) to differentiate the two sets. there is also a "spectator" control and a "beacon" control which both operate on different frequencies to the other ten, so four frequencies are used in total. it is possible to combine the spectator control with the beacon control. competitors start at 2 min intervals and have to visit between 3 and 5 controls out of the first set (according to their age class) before visiting the compulsory spectator control. they then visit the requisite controls from the second set before punching the compulsory beacon control, prior to finishing.