The battery cases have an interesting feature built in that allows them to be attached to each other. Interior closure clip is very sturdy and the case has plenty of room for all the slightly different sized AA batteries that are available today.
Customer Reviews for the product - Plastic battery cases for AA and AAA batteries - Clear Green
I'm a battery nut. I test my batteries and determine their Mah rating and match them in groups. Lately I've needed to group into sets of 8 or 10 cells. They make holders for that size but being able to attach these together means I don't have to have dedicated 8-10 cell holders. I used to keep my batteries in the freezer before the ULSD batteries came around.