in answer to my own question, I think they are based on this text take from an undisclosed competitors website
Alphacool Black Ice GT Stealth II (Dual 120mm radiator)
The Black Ice® GT Stealth 120 is the first true next generation PC radiator designed for uncompromising performance and stealth silent operation. The GTS120 boasts of a radically redesigned Black Ice® core technology that maximizes heat transfer efficiency and maintains effectively the same compact profile of the Black Ice® Pro.
In response to this trend, HWLabs' approach was not one of compromise, but one of leading evolution.