I bought the exact kit from rimfire magic for my cz, takes about 15 mins to fit and does the job whats required of them. "BUT" just be wary, you get 2 tubes of different gauge to fit over the pin and you get 3 springs in different strenghts, if you set it too keen it can and does go off by tapping the butt on the ground. It does make it a whole lot better and would definately recommend buying it.