Yep, The 3 watt LEDs are great for 3+ D cell Maglites with a job, but for general use a 1 Watt emitter is more than enough considering the larger reflector of D cell lights. My 2-D Mag with the 1 Watt emitter focuses just fine. The 3-D with the 3 Watt emitter has a beam just as focused but with the head completely tightened. It may have been possible to focus the beam a bit more, but not much.

All I'd seen until reading this thread were the TerraLux emitters which are not cheap. These other LED emitters make it cost effective to upgrade other lights. Thanks.