Our USB receptacles feature a smart chip that recognizes and optimizes the charging power of your electronic devices for fast and efficient charging of tablets, phones, gaming devices, e-readers and a host of other electronic devices. Reaches up to 87% energy efficiency according to DOE and CEC lab testing, which is higher than the average testing result of most similar products in the market. The higher the energy efficiency, the lower it costs you to charge your devices. Circuit Compensation Function ensures constant charging-Voltage and current of USB port to reduce battery loss of your devices. Color: Grey.