What makes a flashlight impressive is the perfect, or near-perfect, merging of form and function. Form often relates to things such as durability, quality of construction, quality of finish, compactness, ergonomics, and aesthetics. Function often relates to things such as total lumen output, throw/spill, beam shape characteristics, color temp, runtime, heat generation/dissipation, and reliability. Beyond these two domains, value for the dollar is often a factor as well. I have never experienced the WOW factor that truly impressed me until I popped a LumensFactory 12V D26 (320 Bulb Lumens) ultra high-pressure lamp assembly into my SureFire 9P+A19 Extender. In terms of function, the beam is just beautiful, with at least 210 torch lumens output, a generously large circular (non oval) white hot spot that is also scorchingly bright, with smooth gradiations to a generous spill. Also along the lines of function, it acheives 60 minutes of runtime on 4 CR123a batteries and draws only 1.25A. In terms of Form, the LumensFactory bulb is a thing of beauty, just as are the SureFire Bulbs, the top of the LumensFactory bulb is frosted to better diffuse the hot spot, and the construction is all-around solid. The SureFire 9P+A19 extender, of course, has excellent construction characterstics, with a thick, easy to grip aluminum body, a reliable twisty, is compact in size, and has a hardened AR coated glass lens. All and all, the perfect merging of Form and Function, and as for value for the dollar ($79[9P]+$20[A19]+$15[12V LA] = $114), it's hard to beat without accepting a lower quality construction.