They are caps. If they fall off you would only get an alarm in your phone because the sensor is not connected to the tire. When I unscrewed from my tires no pressure was lost in the tire and the alarm came in on my phone.
@@tomcruisin9609 Yes.... Waiting on their email response. I contacted them early on about the batteries being basically dead upon arrival. It took them a week to respond....to tell me that some batteries ship dead and I can buy my own. Could not open those either and returned them. Thanks to Amazon.
