Review on Gozens 26-80psi TPMS: Accurate Tire Pressure Monitoring with Valve Stem Cap Tyre Sensor Indicator (32 PSI) by Junior Rojas

So far they've worked great for me. I bought 50psi for my trailer and tested them by depressurizing and they turned yellow at 45psi and started showing red at 35-40psi. It should be noted that when it's yellow it still looks mostly green. What happens is that the green starts to sink in and only shows some yellow towards the end of the cap. As it continues to descend, it shows yellow and red. So I have to look at them very closely to see if yellow shows up. Also, make sure they're tightened well, otherwise air will leak out, but I haven't had any issues with them leaking either.