this is a must for all impulse owners. if you dont have one then get one. it takes out virtually all the side to side play and you will improveyourROFgreatly it is well worth the $38 but for a little cheaper (around $30) you can get a blade trigger whitch is basically the same thing at www.e-paintballoutlet.com. This site specializes with impulses and you can get all the upgrades you want for your impy. the real wermstick is sold at www.wermmods.com who also specializes on impys,shockers,and angels
the only really thing about it is that you have to have a tiny allen wrench to adjust it but thats it
buy it asap, you will not regret it. If you don't belive me just read the other reviews.