There are four power-ups that you can find within boxes, or can be traded for using a coin at a kiosk.
The power-ups persist throughout the remainder of your run and will build upon each other.
Damage Power-up - Red (Skull)
Accuracy Power-up - Yellow (Crosshair)
Capacity Power-up - Blue (Bullets in-line)
Fire Rate Power-up - Purple (Bullets flying)