2: Reconnecting paired devices
Check that the headphones are not connected to any Bluetooth device before connecting.
Turn on the Bluetooth function of your mobile device.
For details, see the Owner’s Manual of the Bluetooth device that you want to connect.
Press and hold the 
button for approximately 2 seconds while the headphones are powered off.
button for approximately 2 seconds while the headphones are powered off.The Bluetooth LED flashes for approximately 1.5 seconds and the headphones power on before automatically connecting to the Bluetooth device.
When the Bluetooth connection is established, the Bluetooth LED lights for approximately 2.5 seconds.
If the vibration function is on, the neckband vibrates once when the power turns on and three times when the Bluetooth connection is established.link
If the Bluetooth connection is not made automatically, select “DENON AH-C820W” from the list of devices displayed on the screen of your Bluetooth device.
Playing back music on the Bluetooth device.
Music played back on the connected Bluetooth device is output from the headphones.