I purchased the Tire Minder 4 years ago directly from the manufacturer. I have nothing but good things to say about it. I replace the batteries and the rubber seals once per year. It works! It alerted me to a slow leak in the valve extension in a rear tire. I changed to one piece extensions and have not had an issue since. I like the mode where you can tell it to re-read all of the tires. I use that before I start out. I have the sensors on the coach and toad tires. I have received excellent customer support from the manufacturer.