diff --git a/src/main/java/org/sert2521/powerup/util/Oi.kt b/src/main/java/org/sert2521/powerup/util/Oi.kt
index a3c63dc..ff531b3 100644
--- a/src/main/java/org/sert2521/powerup/util/Oi.kt
+++ b/src/main/java/org/sert2521/powerup/util/Oi.kt
@@ -4,12 +4,16 @@ import edu.wpi.first.wpilibj.Joystick
 import edu.wpi.first.wpilibj.Preferences
 import edu.wpi.first.wpilibj.XboxController
 
+// Driver joysticks. Left and right used for tank drive, only right used for arcade drive.
 val leftJoystick = Joystick(LEFT_STICK_PORT)
 val rightJoystick = Joystick(RIGHT_STICK_PORT)
-val secondaryJoystick = Joystick(SECONDARY_STICK_PORT)
 
+// Driver controller. Used in "controller" control mode.
 val controller = XboxController(CONTROLLER_PORT)
 
+// Gunner joystick.
+val secondaryJoystick = Joystick(SECONDARY_STICK_PORT)
+
 val controlMode
     get() = Preferences.getInstance().getString("control_mode", null).let {
         when (it) {