I bought this after having a discount on fitting my new tyres. I saved a lot of money, but the tire pressure didn't match the car's readings. It's that easy to use. Insert the 9 volt battery, go to your GM product and when the tire pressure shows on the dash, hold the reset button. You will be asked if you want to relearn the tire pressure. Press Yes, the horn will beep twice, turn it off and point the sensor antenna under the valve stem at the rubber tire. When your horn sounds, the tire is done. Do each hoop, and when you're done, the horn will blast twice in short bursts. Don't trust a single valve gauge. I found that my expensive gauge was wrong and my cheap ones were perfect. That works great! I used it on a 2012 Chevrolet Equanox and a 2015 Chevy Silverado. I've read that after you flip your tires, you should check the pressure with this gauge. It is very important to follow the instructions! Start with the left front, then right front, right back, then left back. Point the monitor at the tire under the valve, NOT at the wheel. If you follow the instructions, you will have success. Good quality product and accurate.