Giancarlo
(Giancarlo)
156
When they write that 21700 are supported they mean just the flat top ones. In fact, often you read IMR 21700 (which means flat top). But the IMR 21700 is supported by many old chargers! In my old XTar VC Dragon a flat top 21700 fits wonderfully. But if you want to be sure to charge any 21700, then you need bays 77mm long (the Nitecore NL 21700 button top is 76,9mm long)
Also, sometimes even the IMR needs a button top. For example, the new Lumintop GT94X works with IMR 21700 button top.