I have a 917 lux3 PR-T head on my UBH. All I can say is WOW. It's about as bright as my e2e on fresh batts,and has an even tighter beam than the e2e. Really, if you want a small, bright, led turbo head, then you won't regret buying or building one. I don't know the runtime, though. I'm still mezmerized by the beam! /ubbthreads/images/graemlins/ooo.gif BTW, I paid $115 for mine complete from McGizmo in the BS/T mods forum.