As far as the Petzl goes, you can get screw based replacement bulbs. But to be useful its gotta be a cluster of 5mm leds (not sure they make it anymore), and not a 1W or 3W side emitter. The reason is that the Petzl reflector isn't optimized to capture the light so you just get a dim flood. I know, I found that out $20 bucks later.