[bruno]

Yes,the bar is adjustable,and locked in place by two M5 s/s grub screws.
The stopper just touches the string at brace.
The stopper is a Sims stabiliser enhancer so is not just ordinary rubber but navcom material which really does absorb shock.
Hoyt are claiming their system reduces string oscilation by 70%.
On non parallel limb bows this type of device stops some of the forward 'kick' felt in the hand on release.
At the moment in the states STS are at a show where they are dry-firing bows on their trade stand to show how a bow will survive this misuse with a STS fitted.
Apparently they have dry-fired a PSE over ninety times!!