Got mine today and installed two of them. First took about 5 minutes as I had to learn it real quick and the next was about 2 minutes. For anyone installing them here is an easy way. Put the level on the scope where you want it and screw in the screw until you are about 1/2-1/4 turn off snug. Get the rifle/scope level. Turn the whole level assembly until about 1/3 of the bubble is on the left center line of the level. Then as you tighten it the bubble will move towards the level point. It should be leveled when you are snugged up tight with holding the small end of allen wrench. Worked like a charm on both mine. Just like as you tighten down rings and do one side and then the other and the scope moves in and out of level slightly.

Here are some pics. I found the placement in front of front ring worked well as laying behind the rifle the level is just over the parallax knob and easy to see but not blocking anything. Feels solid and well built and for $49 not a bad deal at all. Here are some pics.