You need these to carry some spare CR123A batteries. Not only will the batteries be protected, but you won't have to pay outrageous prices for them at a grocery store or hardware store while on the road when the ones you have run down.

Great case for your batteries. Easy to take with you. Strong, well made.

This is a really good way to keep a couple CR123 batteries handy. It is a decent made little box.

Such a cheap and easy way to ensure safe storage of your spares. I always worry about throwing batts in a pack with the buttons and tailcaps exposed. They could easily short out on objects. And the worry is not so much fear of fire, but the batts getting drained. Even if they only drain 25-50%, thats still significant loss of runtime in your light. Plus the case offers protection from water/moisture, especially if something spills on or in your pack. Get several so you can stash them in different locations

If you are prepared and always carry extra batteries, these cases make it easy and simple. Always have these on hand!