These have been around for a while for specific phone brands since each manufacturer had to have their own special port for their charger. As the phone manufacturers started to standardize around mini and then micro-USB, Energizer seemed slow to catch on to that move and their proprietary-tip portable chargers were all that were available.
You can store the adapter tips inside the charger when you’re not using it which I plan to do since batteries retain their power when kept out of the circuit when not in use. Since my flashlight and camera take the same batteries I plan to use the charger with batteries that are not completely dead but won’t drive the camera anymore. The charger is not made of the sturdiest plastic and probably won’t appreciate too many drops. The connector tabs in the cap certainly won’t withstand much. Treat it like you do your camera and you’ll probably be okay.
I plan to keep one in the car and one in my EDC bag. It won’t be the first thing I reach for to charge something. But it’ll serve as a backup.
I found these on woot.com for 2 for $3.99. I’m seeing prices from $9.99 to $25 on Amazon for just one. I got a good deal on them at woot. I don’t know when that will come around again. Basically the charger was free for me since two Energizer lithium AA batteries usually cost about $4. Check woot periodically to see if it comes back around.