This is the O-ring kit for the 1st generation TST cap sensor. When you change the batteries in your Cap sensors you will need this kit to replace the O-rings, screws, and valve stem gaskets if needed. This kit also includes a Philips screwdriver that is the perfect size for the screws that you will need to remove to replace the batteries. This kit has all the replacement pieces for 6 sensors. If you are changing the batteries in more than 6 sensors then order as many kits as you will need to get to your number. This o-ring kit includes: * 6 O-Rings * 6 Valve Stem Gaskets * 12 Replacement Screws for the Battery Cover * 1 Philips Screw Driver ATTENTION: If you have generation 2 TST cap sensors then you will need a generation 2 O-ring kit. Be sure to look at the pictures on this listing to match up which cap sensors you have. If you have the cap sensor with the spinning outer cap as the anti-theft device then you have generation 1 Cap sensors.