I installed 3 of the D120's on a 180g tank today to replace the T5 fixture that caught fire. I knew that since the tank was so deep and that the light needed to completely mimic a T5 fixture as much as possible, I decided to remove some of the lenses for better coverage. You only need one tool- a Phillips screwdriver.
The first two pictures are what a standard D120 looks like out of the box- except for the lenses that hve been removed.
Inside the case. clean and simple.
6 more screws to remove the board.
the inside of the housing.
the board with snap on lenses.
3 in a hood.
the tank.
Lights are on at full intensity and colors appear to be rendered nicely.