I’ll have to weigh some… the 21700’s are 5mm narrower but also 5mm longer so the size issue should very nearly be a wash…
Edit: An 4500mAh 26650 Golisi Gold is barely a half ounce heavier than a 3000mAh Samsung 30T, so I really can’t see weight being a problem. True, the 26650 is almost a quarter of an inch wider, but it’s also the same measure shorter. So again, the differences are so small as to be very nearly unrecognizable. If you are so close to failure at carrying weight that a mere 1/2 oz could make or break you, then the problems you face are much larger than which battery selection to choose.
I understand that carrying a wider light, even less than a quarter inch wider, in silk suit pants might well be problematic, but then, anything of any comparable size would also be an issue. At which point, pocket carry would have to be dismissed and a belt carrier figured out. This light offers unparalleled output for it’s size, and it does that by using a readily available 26650 format. Granted, the 21700 is making inroads towards popularity in Li-ion cell choices but still it’s availability is much more limited than the 26650.
A neck light may well be of consideration if carrying a flashlight is problematic. Output and run time will suffer, but then, that’s what compromise is made of…