Colin at Sp Filling aka One Less Charlie made all the mods for my Blasers. He has a selection of different types. The engineering is fantastic on all of them as they are built to very high tolerances. Noise reduction is superb and recoil reduced so that all one feels is a gentle shove. One particular model is very clever in that it can be threaded to various sized barrels, by virtue of switching the screw fitting on the mod. I haven't et Colin but have spoken to him several times and he is a gent to deal with.