Vests, or packs, are strapped onto players, and have on them a number of sensors encased in clear plastic which are designed to detect the infrared light which is shot by the phasors. Six sensors are located on the front and back of the pack, on each shoulder and on the phasor itself. The sensors are surrounded by coloured LEDs which light up in the colour of the player's team. Players are known to be active when their pack lights are flashing. When a player's sensors are shot by another player, the player is said to be deactivated, and will remain this way for a number of seconds. During this time the player's sensors and pack lights are turned off, along with the player's phasor, so he or she cannot shoot for this time either. The player will be reactivated after a period of time that differs depending on the game's settings.