I've got one that I took off recently. It is just the top part and is described as
"Flatline Ops Leupold Mark 4 Articulating Scope Level 30mm Matte"
The midway USA part number is Product #: 492041
On your question. I'm a big fan of their levels. I have 5-6 different brands and believe they rank at the top. The only reason I took this off was because I wanted to reduce weight and went to Lite-weight Talleys versus a full rail and then rings. I was hoping that I could put this on the talleys but the holes didn't quite line up. It was designed to replace the top part of Mark 4 rings but....I think I had it on top of a pair of ultra-lite nightforce rings. Not sure on that I would have to check.
I would sell the entire setup that I took off....the 20 moa rail (TPS I think), the 30mm rings which were lightly lapped to the rail and the level. If your interested in any of it I'll shoot you a price.