When a Drive Form or Summon is triggered, the Drive Gauge's function changes. The Drive Gauge becomes grey and the gauge starts depleting to indicate the time remaining for the Form or Summon's activation. The more damage is dealt, the faster the gauge depletes. When the gauge hits zero, Sora's form or summon deactivates. In Kingdom Hearts II, the Drive Gauge can be upgraded to a maximum capacity of 7. Upgrades are awarded by defeating certain bosses. In Kingdom Hearts II Final Mix, this number is increased to 9 and the awarding battles are slightly changed.