18650 Battery Holder, 2-Slot 3.7V 18650 Battery Storage Box Case with ON/Off Switch 6inch Bare Wire Leads [4-Pack]

The length and width of the cell bays are a bit too small. These seem to be better designed for flat cell top 18650's. I had button top cells, which fit, but are extremely tight - such that you have to pry them back out of the case with a flat edge tool/screwdriver. Also, the diameter of the cell bay is tight enough that if you plan to mount it with the screw holes, you must use at most a #6 flat/beveled screw, or preferably #4, or the height of the screw head will raise the cell high enough to interfere with the cover. Overall, not bad, but an 1/8th of an inch more clearance would help.