I've toyed with the idea of getting one of these things, but as FQ 13 points out, for me it's just not worth the cost, and jumping through all of the legal hoops. The cost of these things is atrocious for what they are, ($1,000.00+), and you pretty much have the same paperwork involved as a full auto, complete with $200.00 tax stamp, and a long waiting period. Bottom line, by the time you're all through it will wind up costing as much or more than the gun you screw it on. From what I understand these things don't last forever and have a limited life, and require frequent, painstaking cleaning. I understand the attraction, but for me it's a high maintenance, low return proposition. I'll stick with my foam ear plugs. Bill T.