BLU TPMS506100 Bluetooth 6 pc External Set 100psi

Tpms works well. I bought this system because I have a chevy express bus 3500 with dualies and wheel covers it takes an hour with a tire guage to check air pressure, because you have to unbolt the rear wheel covers to get a guage on the valve stem. They link to an app on my android phone and it seems to flawlessly connect to my phone, however you must open the app and leave it open to be updated to any alert while driving. This is the reason for 4 stars not 5. It does mostly what I need it to by giving me real-time tire pressures without crawling around on the ground for an hour.