I have one in my 4 D cell Maglite. There are some photos of it installed here:
http://www.flickr.com/photos/locoboy5150/4331208321/in/set-72157623355387676/
http://www.flickr.com/photos/locoboy5150/4331211391/in/set-72157623355387676/
http://www.flickr.com/photos/locoboy5150/4495680684/in/set-72157623355387676/
http://www.flickr.com/photos/locoboy5150/4495686320/in/set-72157623355387676/
Note that the TLE-300M-EX is cheaper here at these two dealers:
http://www.aexpertsecurity.com/index.php?item=1105
http://www.batteryjunction.com/tle-300m-ex.html
The drop in is simple to install. If you know how to change a stock Maglite bulb and if you can read and follow the simple Terralux instructions, it will be a piece of cake. It took me about 10 minutes total to make the conversion.
I did make one change to the standard Terralux installation though. I covered the top of the Maglite body tube and the flat portion of the head, both parts that the TLE-300M-EX rests against when installed properly, with Arctic Silver 5 thermal compound. Then I screwed in the TLE-300m-EX. I added the Arctic Silver 5 to transfer the LEDs' heat to the aluminum flashlight body and head to keep them cooler. Poor heat dissipation is a known problem with these Terralux (and most other brands as well) Maglite drop-in upgrades. The Arctic Silver 5 works great and the top of my Maglite gets nice and warm, as it should during use.
I don't really know about the durability of the Terralux drop in because I have never beaten up my Maglite. I do like the quality of it though. It is built well and I have not had any problems with it. The beam pattern is strange though because it uses optics on the LEDs and not reflectors. The individual LEDs each project a square beam pattern due to the optics, just like what you see from an LED light with an aspheric lens. When you have three of those square beam patterns put together, then you get an unusual star shaped beam pattern with sharp points. It's really hard to describe.
I'm not much of a white wall hunter when it comes to flashlights, so the unusual beam pattern doesn't bother me at all. When I use the TLE-300M-EX outside, the beam pattern is perfectly fine. It does not have any spill though. It just has one extremely wide star shaped hot spot. It is very good at illuminating a very wide area with an extremely bright light. See Big Chelis' light measurements thread in the LED forum for lumens readings of my TLE-300M-EX. It is very bright, no doubt about that. It is noticeably brighter than my Fenix TK40.
My honest advice is don't buy the TLE-300M-EX if:
- You love looking at pretty beam patterns on white walls.
- You need to throw a beam of light a far distance.
- You don't know how to change a stock Maglite bulb and don't want to even attempt it.
If you do a search for Terralux, you'll find many other CPF reviews and opinions on the TLE-300M-EX, including my own.