Airmarksman Bubble Level

Agreed, that is all I use for the same reason. This, however, looks to be adjustable. I will say I think I would need the gun in a vice to loosen the rail screws in order to adjust, the scope mounted ones are pretty easy to set up. It would be nice to have an adjustable level that isn't hiding anything on the scope knobs or conversely hidden by the scope knobs, depending on your set-up. But is this aluminum or plastic? I wont add plastic to one of my guns unless it is the only option for something I "need".