They work very well from the time they are tightened securely.
At first, I had moderately tight. Consequently, larger (my teens) a little lazy preferred Pulling on cables rather than around the handles to unlock the system.
I then decided to squeeze harder. The opening becomes slightly difficult: you have to press both buttons at once, and when it is very tight, it is harder but still doable (even for teens :-)
To summarize, they are fine.
