I believe Isopure was the original clear whey RTD protein shake. There are a few other brands out now. Anyone use them? Vitamin Shoppe had a $1 sale of the MyProtein brand the other week and I bought two to try. They were decent. I got Lemonade flavor. It really tasted like lemonade. A little sweet though. The clerk there told me that the ready to drink ones sold really well, but the tubs of powder did not. That nearly everyone brought them back for refunds and they were considering dropping that brand. Apparently, despite the most vigorous efforts of man, blender and prayer, they did not dissolve completely. There were clumps in there that the RTDs didn't seem to have.
Sounds like it is basically EAAs from the way it foams and clumps.