The battery is very handy, light and well finished. He warms up during charging and discharging hardly. Unfortunately, the capacity of 3000 mAh can be reached nowhere near. My smartphone (Lumia 535 1950 mAh) can not once fully charge. The external battery breaks down at 94%. That's about 1/3 less capacity than specified, so I am sending him back. For processing, weight and handling still 3 stars.