1996alnl -The 2009 KL4 120 lumen head will not run on a single CR123. It will, however run very well on a single RCR123. I use a battery station RCR123 with their charger. Battery Station claims that these cells come off the charger at 4.2v. I run a Vital Gear FB1 HA body with the SF KL4 head and the anodizing matches perfectly. Pocket rocket!
Well that's good to know;
So the newer version will work with a 17670 cell then, for the extra runtime.
Awsome..