When the original Berlin protein skimmer came out in 1993, it was a big deal at the aquarium store I worked at. No other skimmer was like it with it's internal configuration that extended water/air contact time. Now the new Berlin X2 protein skimmer claims a 50% increase in skimmer performance over the original model.
Berlin X2 Protein Skimmer by Red Sea
The X2 skimmer also comes with a patented FoamView collection cup that allows for easy viewing of skimmate level within the cup.
The Berlin X2 is available with a pinwheel (Turbo model) or venturi (Venturi model). The Turbo is rated for aquariums up to 225 gallons and the venturi is good for aquariums up to 150 gallons in size.
More info:
Red Sea Berlin X2 Venturi Protein Skimmer (Saltwater Aquarium Supplies > Protein Skimmers > Hang On > Venturi With Needle Wheel )