This tiny coin cell battery holder is ideal for small portable or wearable projects. It holds two 20mm CR2032 coin cells in series to generate 6V nominal. CR2032 tends to have about 220mAh capacity so this holder would give you 6V @ 220mAh with two cells.
The holder is made of plastic and snaps open and closed. You can tape it closed if you need more security than just the plastic snap. A nice extra is the on/off switch up top. We had the factory place a 2mm JST PH connector on the end but you can cut it off if you want to solder on a different connector.