I used the flat panels with the pigtail adapters in a previous TT. They were much brighter than any of the plug-in bulb replacements and all of the light is directed where it should go - not at a reflector in the fixture. The flat panel sticks to the reflector with two-sided tape and plugs into the socket with one of the supplied pigtails. I prefer the warmer color temps to the "blue" light frequencies.
Rob