TOPITEMS Charger,Qi Wireless Power Charger Charging Pad For Samsung Galaxy S7/S7 Edge (Blue) Charging Distance:4-10mm Ultrathin, lightweight and portable, good for using at home, office, public area, etc Frequency: 100-200kHz Power transform efficiency: &gt;70% Short-circuit protection of the receiver to avoid overcharge & overheating, security and reliable