Can you tell the difference between 15psi and 17psi? No you can&';t. We can&';t either, but the Blackburn Honest Digital Pressure Guage can. Today&';s wider, lower pressure tires are more pressure-critical than back when we just used to put as much pressure in as the pump could stand. It&';s not about fending off flats these days, it&';s about grip. And the difference between too much and not enough can be as little as a couple of pounds of pressure. The days of &';giving it a squeeze&'; are over. You need our help. 1.Swivel/Dual Head 2.Backlit Display 3.Accurate within 1% of pressure 4.90 psi max 5.Includes Frame Mount