I think it's TPMS. Bought to replace a burned out one. It had some good reviews so I bought it. The manual is good, it sucks. I asked the seller a few questions and all I got was a "read the manual" response. I finally got lucky and set my tire pressure to PSI (don't know how I did that, just pushed buttons). I cannot change the temperature from C to F. I've tried adjusting the high low pressure but it's fine. The block itself will do what I want. Accuracy is questionable - tire pressure appears to be 2lbs lower than actual. not bad. I would recommend doing more research before purchasing this device.