Having a hold rotate, or "spin" while you are climbing can be annoying. Here at Uncarved Block we are slowly adding a cure for this to all our holds. This can happen due to the design of the holds allowing higher than normal amount of leverage being applied to the hold, or to any hold on a wall without a lot of texture on it.
You may have noticed some of our holds now come with another smaller hole in them. This is for a 10 gauge wood screw to stop holds from spinning. While using the hole is not nesccesary, you now have the option to use it, should the problem arise.
The screwhole also has a washer, which will reduce the possiblitly of counter sinking the head of the screw into the hold if you happen to get carried away when tightening. Using the screw is only to prevent the hold spinning it is not to secure the hold to the wall, that is what the bolt is for.