I don't want to grave dig a thread but this is relevant.
Just wanted to shoot a quick review on the one I bought. See above for the particular model. First, it didn't really fulfill my "sturdy" expectation, not even the slightest. Within the first few weeks the top part where the key goes in came out completely and I had to super glue it back in because the threads were stripped out. It was odd since I had never taken it off before I wondered how it could have been stripped out. After I superglued it the contacts were having trouble staying together. In that top part, there are two contacts that float and are pressed together by the pressure of the batteries. I don't know why they came up with a floating contact like that, it seems like it has no practical use. Why not just put a stationary contact? Either way after supergluing the top part, I wasn't able to get back in it to move or clean the contacts so I had to go in from the other side and basically force a battery to push them together. I don't know what type of material that holds the contacts in place is but I assume it's Teflon. Now that piece is at an odd angle but the laser works. I just hope it doesn't fall apart or give me more problems. It's working well and the beam is strong still, but it's slowly falling apart.
Again sorry for the grave dig, just wanted to share my experience with it.