My XTAR X4 Extended is able to charge an Olight 18650 (not too surprised). However, it is somehow also able to charge the Olight 21700 despite the plastic ring around the positive
Akumulator 3,6V Olight 21700 5000 mAh - sklep Militaria.pl
Olight Warrior X Pro Flashlight Review – The Best Cree XHP35.2 HI Flashlight? - ZeroAir Reviews