The Alligator Sens.it Snap-in Valve Stem has a patented rubber lip at the base, which increases the surface area and the friction of the valve against the rim. The flexible lip allows the for a tighter fit, which helps prevent snap-in TPMS sensors from rotating and breaking. The more the sensor rotates, the more prone the TPMS system becomes to malfunctioning. At 90-degree rotation, the sensor is unable to recognize if the car is in motion or not. A rotated sensor also can break when the tire bead is pushed down during service.