Pretty much any of them will do the job as long as they have a zero button. I use the Align gauge because that was all that was out when I got it. And I paid substantially more for mine lol. But any of them will work. Off to the side or center, that doesn't really matter. Mine is centered, but what matters is that the main components, the read out and the electronics, are over the blade itself so as to not put too much stress on the servos.