Review on TST Tire Pressure Sensor Tow Car Pack: Enhance Performance with TST 507 Systems by Chris Crisler

I bought 4 new ones for my 5th wheel. I had a set from 2015 that worked fine, but one stopped working last fall (even with a fresh battery). They work just like the old ones and are programmed the same way. My old ones were put on with a special tool as the sensor rotated freely on the base when tightened. A special key was needed to grab the base and remove it. The new ones are no longer free spins. They use a separate nut that is first slid onto the stem, then screwed onto the sensor, and then using the special wrench provided, press the first nut against the sensor so it cannot be removed by hand. Special keys for old versions are not interchangeable with new ones.