I have read other people's comments about their experiences with these sensors. Some were unhappy with inaccurate readings and the fact that the gauge didn't hold pressure after it was removed from the tire valve stem. I ordered one anyway, hoping to get the sensor as advertised. I was dismayed with the pressure gauge I received as it doesn't accurately measure or keep the pressure either! WAITING! I looked at the gauge and noticed that the protective rubber sleeve they add to cover the gauge was "pinched" by the stem assembly as it was screwed onto the gauge. This prevented the stem from making full contact and sealing the "O-ring" at the base of the stem. I unscrewed the entire rod from the gauge thread and rearranged the protective cover to avoid pinching it when unscrewing the gauge rod. WA-LA! The meter works perfectly! Now it stores pressure so you can read the pressure after you take it off the tire, and it does it with precision!