Swimming One Way Shouting Machine Waterproof Wireless Bluetooth Connection Music Playback Swimming Training Device for Surfing Diving Item Type: Swimming Training Device Material: PVC Weight: Approx. 260g / 9.2oz Battery (Built in Battery): Lithium Battery Model: 506065 2000MAH Continuous Operation Time: 4 Hours (Continuous Operation Not Recommended, Use Shouting Mode) Number of Connected Headphones: 7 Groups, Connecting 200 Charging: USB 5V Full Charge Time: 3 Hours Standby Time: 7 Days Transmission Distance: 50m / 164ft Bluetooth Protocol: 5.0 Usage: Head Worn Product Size Of Host Without Antenna Installed: Approx. 13x6cm / 5.1x2.4in Purpose: Swimming Pool, Surfing, Diving, Water Skiing, Teaching Built in microphone mode: After powering on, the host defaults to the built in microphone mode. Hold down the send key (PTT key) and speak towards the built in microphone to transmit voice. Release the send key (PTT key) to stop transmission. External microphone mode: When the matching external microphone is inserted into the Mic interface, the host will automatically enter the external microphone mode. The built-in microphone will be disabled at this time, and the host will continue to transmit voices through the external microphone without pressing the send key (PTT key). In this mode, pressing the send key (PTT key) for 5 seconds will pause the transmission signal, and pressing the send key (PTT key) for 3 seconds will resume continuous transmission, repeating this cycle. External sound source mode: When an external sound source is inserted into the Line-In interface, the host will automatically enter the external sound source mode. At this time, both microphones are disabled, and the host will continuously transmit the signal of the external sound source. In this mode, pressing the send key (PTT key) for 5 seconds will pause the transmission signal, and pressing the send key (PTT key) for 3 seconds will resume continuous transmission, repeating this cycle. Bluetooth slave mode (high end version): When the host is in the built in microphone mode, press and hold Function key 1 to enter the Bluetooth slave mode. At this time, the host can be seen as a Bluetooth slave device, which can be found in the Bluetooth device list of the phone. When the connection is successful, you can transmit the sound from the phone to the training headphones through the host. Click to play music on the phone, transmit the music, and stop playing to stop transmission. Press and hold function key 1 or 2 to switch to the next mode. Bluetooth master mode (high end version): When the host is in the built in microphone mode, press and hold Function key 2 to enter the Bluetooth master mode. At this time, the host can be seen as a Bluetooth master device similar to a phone. In this mode, the host will automatically connect to the surrounding matching Bluetooth headphones. When the connection is successful, the host will transmit the sound received from the Bluetooth headphones to the training headphones. Double click the power button to search for nearby headphones and connect them. After the connection is successful, press and hold PTT to transmit the voice of the Bluetooth headset, and press briefly to stop transmission. Press and hold function key 1 or 2 to switch to the next mode. Adjusting transmission channels matching training headphones: Regardless of the mode in which the host is, simply rotate the large adjustment button in the center of the host to switch channels. As the channel changes, the indicator light of the host will also change. Just make sure that the indicator light of the training headphones and the host are the same color, and the headphones will receive the sound sent out by the transmitter. Note: Channels 01-07 of the host are compatible with traditional transmitters, and the indicator light colors are also compatible