Specification: Material: ABS Dimensions: 15x15x7.1 cm Weight: 88g Input voltage: 9V / 2A Power: 10W Working distance: <5 mm Charging efficiency: 70% -76%Qi is one of the most modern methods of wireless energy transfer using inductive charging. It is designed for smartphones equipped with this technology. The system is based on the phenomenon of electromagnetic induction between two coils. The charger has a power transmitter that contains a coil that generates an oscillating magnetic field and a magnetic field that induces alternating current in the smartphone.