Genuine Samsung 40T 21700 are expensive and difficult to find in our country (and most foreign stores have difficulty shipping to my country).
I’ve seen a local store carry this Vapcell K40 (I bought a pair), but have not really use these batteries yet.
(btw, the wrapper color does not appear to be “black”, but more like a “dark gold brown” color)
Using your battery comparator, the discharge graphs of the Vapcell K40 appear to track quite similar to the Samsung 40T in almost all discharge currents.
(However, based on my simple visual observation of the Vapcell K40 battery vs a Samsung 40T battery, I think the K40 is not a 40T, because the K40 is slightly lighter in weight and also slightly longer in length compared to a genuine 40T.)
You’re probably right… referencing HKJ’s reviews of the LR2170LA, the weight, height & diameter of the Vapcell K40 seems to be a very close match,
although HKJ’s review of the LR2170LA has just slightly less tested capacity than the Vapcell K40 (which in turn has slightly less capacity than 40T), but these 3 batteries’ discharge graph (using the battery comparator) track very closely in almost all discharge currents, other than the slightly less capacity.