It can only handle unprotected flat tops.
Button tops can be inserted, but they are almost impossible to remove, and even putting them in is a chore.
Protected cells are out of the question. Too long, and even if you managed to put them in, you would not be able to pull them out.
Smallest DIY 2 18650 power bank that I have seen, and the finish is so good. Smooth rubber feel, but gets dirty quite easily.
It only has a micro-USB port for charging and a USB-A for output. I would have preferred having USB-A out with QC 3.0 since it operates 2 cells, and 18W is possible then with even laptop pulls.
One nice feature is that I don’t have to worry about hurting cells that have SOC: it is the first non dedicated charger that I’ve seen that had two separate charging channels! This is what XTAR meant by separate charging of the lowest charged battery.
In output, it combines the parallel output of the cells, but in charge, it charges the lowest voltage cell first.
It works, as I have tried putting 2 cells with different voltages(3.8V vs 4.24V), and they didn’t discharge into each other. Great stuff.
It has a max power input of 10W, and a max power output of 10W. The package includes a micro-USB cable, and a small manual explaining things.
BTW, the cells used are LG D1 laptop pulls.
Both are tested to be 2500mAh cells at 2A using my constant current tester, so they are good.
Edit: Sorry for the poor layout, but I don’t know how to link pics on mobile, and formatting is poor. I will correct this once I get home on my PC.