1.The new digital tire pressure monitor is no sensor and its sensor position is in the car OBD. 2.Its working principle: through connect car computer data bus OBD plug,OBD directly obtains the ABS data of the car ,then read and monitor the tire speed and pressure value changes. 3.When the tire leaks more than 25%, the radius of the tire will be changed smaller, tire speed becomes faster, the monitor will alarm. 4.When the tire is high pressure, the radius of the tire will be changed larger, tire speed becomes , the monitors will alarm. 5.Powerful chip function, fast sensing of abnormal, accurate alarm. Product: digital tire pressure monitoring screen Applicable model: for Functions: Digital four wheel display, OBD technology, low pressure prompt, maintenance prompt, fatigue driving prompt Installation mode: all free wiring Model Number: Car Tire Pressure Monitor Feature 1: Car Tire Pressure Monitor OBD TPMS LCD Diagnostic Feature 2: PHEV Xpander Eclipse . Material:plastic colour:black Package Contents: 1 x host 1 x harness Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.