I bought this product as the name Michelin to me means they should know something about tyres. When I tried to use it,I found the gauge offered three different forms of pressure measurement, and I thought that if I selected PSI that would be the reading I would get. However, when I tried to use it the meter showed "0.00" then "28.88" then "14" and so on whilst the pump was doing an impression of someone shaking a can of nails. After about five minutes I took a reading of my tyre using a manual tyre gauge only to find the pressure had not changed from when I started. So back to the instructions to find out what I had done wrong and followed the instructions explicitedly. The same thing happened. So in frustration I decided that I would return the item, fotunately I had purchased this from Amazon and the return procedure was simple and faultless. If only the pump was half as good. I have reverted back to my trusty old foot pump which is simple and effective. Perhaps I was just unlucky.