I have a moderate set of Bessey REVO clamps -- which are the best for many purposes. However this economy clamp is also quite good for a lightweight bench clamp. It is typical good Bessey quality. I have several in 12" and 18". For light use, when a REVO is too much, these are the clamps I grab.
To adjust the clamp opening, you press the grab-bars beside the adjustment handle. To adjust the clamp closed, push the adjustable member closed. The diameter of the clamp screw is not great, so high pressure is not an option.
This is a good lightweight clamp, and I recommend it for lightweight uses.