http://itunes.apple.com/app/4x4-gyroscope-clinometer/id387614872?mt=8 Before use, on level ground, mount the phone in landscape mode on your truck, with volume buttons on top, level with the dashboard. After this, no further changes are needed, it will automatically use the Gyro and gravity to know the tilt and roll of the vehicle. You can use the RESET button to level the app if your mount is non level, or needs to be at an angle.
