Seen it for sale but think its just a big waste of money. If Barrel harmonics are really such a problem you could just experiment and put a dollop of clear silicone caulking between your stock and barrel at different points or at more than one point and it should adjust your barrel harmonics far more agressivley and without any thingamajigs hanging off your barrel. You could even tie a five pound weight off the front of your barrel with a string and take a few shots off the bench to see if harmonics are truly a problem. Anything will technically alter your harmonics and where on the stock you rest your rifle while bench shooting can even make a differenc. However if you find one of your guns were to show such problems and harmonics really altered the guns POA to the point where a single pressure point in the stock couldn't cure it I think the best bet would probably be to get rid of it. Hope it helps.