Easy. Think of it as a 2 cell Q3. Head (bezel with lens and reflector), 2 cell body, and a standard tail cap with a High/Low switch.
The only mildly hard thing about disassembly is getting the head to unscrew from the body. There is some thread lock glue on the head threads and you either need to soften up the glue before twisting or very firmly grip the head and body with leather work gloves and reef on it really hard to break the threadlock. Strap wrenches work great for this job.
I've always just heated up the side of the head where the threads are with a small hair dryer and then twisted the head off while wearing work gloves.