Good system but not recommended for trailers. They stated it wasn't for trailers, but some reviewers seem to have had luck with their trailers, so I gave it a try. During our trip, the rear axle was hardly updated. It was still showing initial PSI after 2 hours of driving while the front axle was showing the typical PSI increase due to heat. Not reliable enough to trust this app but I still give it 5 stars as they warned me not to use it for a trailer. for followers.