A very practical way of storing batteries safely. If you have a digital camera which takes ordinary AA batteries (normally you would use rechargeable ones), such as many Cannons do, you will want to capitalise on that by taking spare ones with you (usually impossible for most people with a built-in battery to recharge). This way you can easily take two spare pairs in the camera case, and house the ones you take out. The 5 packs offer is splendid value .
I had had a similar idea before, and stored batteries in little screw-top tubs which I had to hand, but this is much more convenient.