Like Sean said, it depends on what your running it on. If your using a Maxflow reg, you can just use something like a Voodoo foregrip which basically does nothing apart from being something you can hold the marker with. If you are using any other air system or Co2, you will need some sort of vert reg i.e. vert Max-flow or AKA Sidewinder because I think anything over 250psi going into the impy will damage it.