Dad just brought home a single 18650 he found at Batteries Plus…
They’ve never had any 18650s I have been able to find. For $9 and some change, you get a 2600 mAh protected cell that is very large. The protection chip moves around, and this light won’t fit into the common budget chargers. It’s too tall and fat and is a hard fit even to most single-celled lights. But in a pinch, this may be an attainable 18650 when you don’t want to wait to have one shipped.