Due to the nature of things Lithium Ion, 18650's tend to vary a bit in length and girth, so sometimes a bit of extra force is required to close this case if one or two 18650's are being stored... this makes for a concern the case will pop open, letting these powerhouse cells free to get into trouble. Double check your case to insure it locks up well. This style closure isn't the type Tenergy employs in its AA and AAA cases, which gives a better sense of secure closure, even making it a bit harder to open. This case closes more securely with the bit thinner CR123A's and RCR123A/16340's. With these the fit is a bit loose, so there's some rattling, but by the same loose fit the cover snaps shut more securely without the resistance of a plump 18650 cell fighting it. I also find that pairing one 18650 with two CR123A's works nicely, but if you pair with two RCR123A/16340's, you may find that due to the variance in length of the RCR123A/16340's maker by maker, two of these placed alongside the 18650 may also interfere with the fit and closing.

Great for holding extra batteries.

Useful for the storage of loose batteries. I have had these plastic cases for a few years now and not one of them has failed yet.

Very good for organization and on the go.

Nice little case that is capable of storing two different styles of batteries.