Really wish I hadn't spent the $$$ on the USO level
I'm in for 2. The first one was the fixed rail level and ended up not having enough real estate between my ring and side focus for the level and ACI.
The second one was the swivel ring style although it works better than the fixed rail type I'm still considering going back to the Scopelevel (if only they were made from metal).
My biggest complaint about the USO's is the bubble is so small and the fluid they use is like gear lube. They are brute tough though.