As lighting technology has evolved efficiency and productivity has gone up. Cooling has become much less of a worry and lamp maintenance costs are greatly reduced. Light spectrum can be customized for the specific type of plants being grown and what stage trey are in. LED's(Light Emitting Diodes) have improved by leaps and bounds since their introduction in the late 1990's. Ceramic Metal Halides, Induction Lighting, and Plasma Lighting are the new kids on the block. One thing is for sure, this isn't your father's HPS.