Peak has produced a number of different lights in the single CR123-A configuration. These included the Glacier Bay, Atlantic, Caribbean, Mediterranean, and the Ranier. All these used the same battery compartments, so if you already have any of these earlier Peaks, you can simply add a LOGAN head to the old body. This also applies to the 2XAA Caribbean which used the same diameter & threads.
Note that quite a few Peak lights over the years have used smaller diameter battery compartments for AAA's, AA's, N Cell's and CR-2's. These include the Matterhorn, Fujiyama, Shasta, Kilimanjaro, Pacific, Baltic and Kino Bay lights. None of these bodies will interchange with LOGAN heads. But for many of these bodies there is now the option of a Volcan head which uses the same emitter, electronic and optics as the Logan.
