IIRC...
the white would be urethane, and then the yellow would be reactive..so the Rhino Pro, i believe...
also, though, they also made Rhino plastic balls in a few different colors as to compliment the reactive line, the Teal Rhino that i own is plastic..soo
Mark MacGregor; Macomb, MI
Current Lineup:
Anaconda, Wicked Seige, Avalanche, Avalanche Urethane, Rattler, Teal Rhino (plastic), 916AT, Nomad Pearl