The small box on the back of rugby players shirts is a GPS tracking device that provides incredibly detailed performance data. The device is commonly referred to as a GPS tracker, although it contains other measuring devices such as a gyroscope, an accelerometer, and a magnetometer. It may also have a heart-rate monitor. The padded casing surrounds the unit, and it is kept in place in between the shoulder blades in something called a "Bro" which works in much the same way as a female athletes sports bra. The GPS tracker measures a host of physical data emitted by the player, such as distance covered, speeds reached, and overall heart rate of players. The device is designed and cleverly positioned to sustain collisions and impacts during the game. The GPS tracking system is used by coaches to track a variety of statistics about every player, and one of the primary uses for tracking systems is to manage a player’s workload to make sure that they stay healthy and able to perform at their peak for the entire season.