* Function:
   This is a new design tire tread depth gauge, it has indicator
   bar that calibrated for measurement
   The contact tip is profiled to work in narrow spaces between 
   tread
   That can warning the tire tread depth is not enough to 
   keep using this tire and you'll hear the "beep" and led 
   will light, so you can easy to  know the tire tread depth is 
   good or not
   You can set the gauge that you'd like to measuring 
   calibration, then put the tip to tire tread, it's easier to 
   know the tire tread depth, and  you don't stoop and read 
   the gauge hard!