U can charge any other 4th device with the extra USB port that comes in the back. I love these headphones so far. Overall very good shoe. They are a tiny bit grow-into big, but not by much. I love the lights on the charger and the “breathing” blue light to let you know it’s charging. I would not recommend the Sabrent audio card for APRS use or anything else. These do not seem authentic! Finally we have a transfer of this extraordinary emotionally powerful film which is full length and with high quality video and audio. I have been wearing Fit Flops for years. Returning them because I cant get them on his feet.