Us optics rail mounted bubble level - U.S. Optics Rail Mounted Swivel Bubble Level

The device is well made, and works just as you would expect. The swivel is worth the extra money because otherwise, unless the level is removed after shooting, it is only a matter of time until the fixed level is accidentally broken off. It is worth noting that the rail mounted level actually indicates whether or not the rail that is part of the rifle is level. A scope reticle still has to be adjusted to be perpendicular to the rail in order for the bubble to help align the rifle and scope. This isn't a big deal, as a properly mounted scope should end up that way, but unless the scope was mounted on a leveled rifle it won't happen.
Pros: Simple, easy to mount and use, and works well.
Cons: It is a pricey indicator of a rifle cant problem.

This review was written in the old system and had content requirements that are different than reviews written today.