I got some of the moonlights from Drs.F&S all pre-wired and ready to be mounted, but after a few weeks, some lights were noticably dimmer than the others and at $30 each, I wasn't getting any more. I still use two of them on my 90 gallon acrylic tank and use museum putty (from Home Depot) to fix them in place at the edge of the opening on top of the tank. Great stuff, stands up to heat from MHs and dousing from water. Good for many uses around the household as well. You can even use it to keep wiring in place...just roll up a wad like gum and stick it where you want it! Comes off clean too.

Moonlights are definitely beneficial for both the viewer and the viewee.

Museum putty! It works!