Piston seal sticks poorly. Once it starts moving it's free, but it takes a little effort to break the o-ring and get it moving. It is difficult to achieve smooth action. The pressure builds up and nothing happens, then it goes on quickly. There will be no problem if higher pressure is applied to the piston (50+ psi is great), but if you're trying to run at low pressure for low forces, friction comes into play. If you want smooth performance at 5-10 psi, this isn't for you. The quality is goodβ¦