Okay I bought this because I got a DOA Mag-lite with LED bulb and I thought I would revive it. No Bone! This is not a replacement for an LED bulb, it is an LED upgrade, albeit not a very good one, to an incandescent bulb. I have an old Mag-Lite with an incandescent bulb, so I used that. It's not as bright, but I expect a fivefold increase in battery life. I keep you updated.