To use it, this is easy: load it ugly nimporte any USB charger 5V / 1A. When charging, an LED rear lights red.
Once fully loaded, the light turns green, the battery is ready for use.
Connected to a device, the green light flashes and the flashing red will soon begin how to show signs of weakness.
As output, it also delivers 5V / 1A to reload, at moderate speed, nimporte any compatible device.
Lightweight and compact, this backup battery can occasionally serve to benefit of a little extra current.
It also provides a lamp which lights up by exerting pressure on the double-close plastic button covering the LED. Practical!