They do work. They help with both noise and vibraton. I have a Truth 2 that has two built in dampeners, and I like it a lot. I also have the original Truth bow, which I added an aftermarket stopper to. It does make it quieter and smoother. Recently I tried an 82nd Airborne with its built in string suppressor. I shot it both with the suppressor off and on. It was a night and day difference. Without it, the bow wantedtovibrate right out of myhand. With it, I could barely feel any vibration at all. I really think it is going to depend on the bow. Some bowsnaturally have very little vibration and are pretty quiet. It might be hard to tell a lot of difference on those bows. Other bows inherently have morevibration, andyou can noticeably tell a difference on those bows. I say they are worth it.