8PCS Car Tire Pressure Monitor Valve Stem Caps, 3 Colors Alarm Tire Indicator Valve Stem Leak Monitor, 2.4Bar 36PSI Tire Pressure Caps for Car Truck Bicycle Motorcycle (Silver)

These did not work out. They were fine for about 2 weeks. Then the top broke off one of them or something. Caused a flat tire. I was relieved when I figured out this was the cause

I purchased these because one of my tires have had a pesky leak for a long time. I put them on all four tires at 35 psi and the indicator showed Green. I slowly removed air and took measurements every 2 psi increments down to 25 psi. The Yellow indicator never showed, but I did get a Red indicator. The point of the TPMS is to see when the pressure drops incrementally, so I could add air at around 28-30 psi without having to take a physical measurement. For this reason, I give the item a 1-star rating because this is a safety issue. I did receive 2-sets of 4. I found that one of the sets had one cap that did not work.