This 8 sensor TST 507 TPMS monitors your tires' pressures and temperatures and reports remotely to a color monitor. Alerts will notify you of any readings outside of your custom high and low alert parameters. It reports up to 4 trailerstowables, and features a user replaceable battery. Flow thru sensors allow you to air the tires without removing the sensor. Note Flow Thru sensors must be used on metal valve stems. If you have rubber valve stems the purchase the TST system with CAP sensors. TST 507 Series 4 RV Cap Sensor Tow Pack. Installation Tool Provided For Towed Vehicles and Trailers. RV Cap Sensor Specs Temperature Operating Range: 40 F 176 F 40 C 80 C; Pressure Range: 1 218 PSI 1 15 BAR; Physical Sensor Size Cap: 0.96 inch (D) x 0.91 inch (H) 24.4 (D) x 23.1 (H) mm; Sensor Weight Cap: 0.59 oz. 16.8 grams