Hmm, That's weird. I believe that my Maglite 4D is much brighter with the LED bulb than with the incandescent. However, I've got the Mag-Lite original LED replacement, 3 watt, not the Nite Ize LED (no wattage on their website, though, 1 watt?). I can't look straight at this LED light, it's simply painful (another self-defense feature )! No problems looking at the incandescent bulb...

Hikin_Jim, "Mag-Lite" in the name means that this bulb does not void the Maglite flashlight Limited Lifetime Warranty. For the other LED replacements you can try to search eBay.