Here is another example of a product from China that uses the worst english to TRY to explain the features but is barely understandable. There are NO instructions with the unit. First you have to charge the battery, that they don't tell you about, via several different methods before it will work. You can use the USB port to charge it, a Garmin power supply , if you have one, or an android phone charging adaptor. During the charging period the light on the bottom glows red. During use the bottom light is blue. I have used the unit with a Sony MP3 player and my iPhone using the headphone jack on both units,and the Garman/Android phone style adaptor port on the speaker unit. Volume controls on the unit work but are slow to react. Other features like the pause work but the EQ button does nothing. All in all the unit works but NEED instruction !