It’s expensive, though. You could buy a 10000mah Xiaomi POwerbank 2 or pro for ~2USD more, so even with free (already owned) 18650 cells, it’s hard to justify. It’s too bad really, it’s the only powerbank with 4x (or 3x) replaceable 18650 cells I have found that both charges and discharges at a decent rate. And using replacable 18650 is nice when you need that extra Wh once or twice a year, and have more 18650 cells lying around.