Depends on if you want throw or flood. KL1 has a throw beam but is an optic, a reflector mod in a KL1 works great! A KL3 will not fit without an E to C adapter. A KL4
is more of a flood type beam and generally costs more too, I'm not sure why. I would
buy a KL1 and put a Seoul and reflector in it, costs the most but I believe is the best
combination. Plus it will be brighter and run longer and not get as hot either.