If you have minimags... I recently purchased an Opalec Newbeam conversion kit and a Terralux Ministar 2. Two thumbs up from me! They are not similar - the Newbeam is pretty much a nice flood - similar to a Trek 4 but brighter. The Ministar2 is brighter than the regular lamp, batteries last longer, and it can be focused (not as well as the incandescent, but more than good enough). I really like both of them!

And for the bigger flashlights - the EverLed PR bulb replacement blows my socks off. They are spendy at about $40US each. I've got one in a 2-D cell maglight and one in a 3 D-cell maglight and they are totally superior to the incandescent bulbs in all ways. If they were $10 cheaper I'd buy some more...

You can read reviews on all of these elsewhere - I'm just posting "real-world" impressions - I like all 3 of these conversions!

No affiliations - just a very satisfied customer!

Tom