Bests & Worsts Reviews from Amazon

You start by putting the appropriate connection on your bike's valve stem, and locking it on with a turn. After pumping up the tire you have to turn the lock the other way to release the valve head. Because of a flaw in the design of the 'smart' valve head, the air in the tire is blows out through the 'smart' valve head. My solution so far is to overfill the tire to compensate for the loss of pressure turning the balky locking mechanism and removing the tightly fitting 'smart' valve head from the bike's valve stem. Wish I'd known about this before buying, so I could have bought a different pump. Buyer beware!