I use this to connect my hearing protection head phones and cell phone. I wear when mowing the lawn and this makes the task more enjoyable. This is a very simple device. Has only one button. After charging, hold button for 3 seconds and a little light will quick flash blue and red. Set up your phone to allow for discovery. Once found allow the connection to take place the light will turn and slowly blink blue. I then renamed on phone so that I could find the connection easy next time. Use the phone for volume and play back control, no controls on device. I placed a piece of velcro on the back of the device and on my headphones, light enough that I don't feel the weight on my phones, works great! I use every time that I mow, leaf blow, or weed whack the lawn, very happy with purchase!
Hold the button a couple seconds to turn it on, keep holding for discovery mode. the light will blink both red and blue at the same time. i can go a couple days with it just chilling, ive noticed the volume varies between a full charge and almost empty battery. when little or no battery is left a loud beep interrumpts the music every 3 seconds, overall a great product for 10 dollars.
Initially this did not work well when I got it... very quiet even at full volume, so I took it apart and resoldered the stereo connections and the power. It is similar to the fairly standard bluetooth board you can buy all over the internet then put into a simple box with a button and battery. I then charged it for a few hours and it worked just fine.