GM rebuild-able pressure tire sensors. One of the easiest to rebuild. Pop the side off Slide the circuit out. Solder replace the common battery. Slide circuit back in place. Crazy glue the cover back. Should be good for another 7 years. best time to catch me: no Saturday, hrs 10-6, Sun-Fri. (if you see something wrong with the price, just tell me about it) Actually you can have these free.