I have these. They are nice. Thin and compact. USB-c is the only charging input which is a slight annoyance. But micro-b to c adapters work. I measured charge current through an adapter to a usb-a wall cube and it was around 1.9 about 1.9 amps, so charging isn’t too slow. The old thicker pack that’s usually 2 for $16 is good too.
This deal comes up often so at this point I have 6 of these… they’re good though. They hold a charge, their capacity is pretty close to the claims and they quick charge my phone. I’ve even used these to add a little charge to a Macbook Pro once, though they really only work if the laptop is off or sleeping nd they won’t charge one fully.