Please make sure both the TOUGH SYSTEM MUSIC and the user device has Bluetooth turned on.For TOUGH SYSTEM MUSIC: Press Bluetooth symbol button to choose Bluetooth mode. Hold down the Bluetooth symbol button on the TOUGH SYSTEM MUSIC for over 1 second for matching, the blue light will flash on the TOUGH SYSTEM MUSIC. (For user device: Please connect it to Bluetooth mode according to its user manual) Please try to re-start user device and delete all matching records of user device, re-match and make sure the range <10 M between TOUGH SYSTEM MUSIC and the user device also ensure that there are no obstacles that could interfere with the connection. If still can’t pair the Bluetooth, please take TOUGH SYSTEM MUSIC to an authorized service agent.