Bluetooth distance: about 15 meters (under barrier-free environment/connected to a pair of headphones)); Bluetooth version: V5.3 Charging time: about 2 hours; Bluetooth transmission playback time: about 9 hours (connected to a pair of headphones) Battery type: polymer lithium battery; Supported protocols: HFP/A2DP/AVRCP Bluetooth encoding: /AAC; Battery capacity: 3.7V 180mAh Note: All technical inforation is subject to actual performance TX transmission mode, pairing and connecting the second device After successfully connecting to the first device, press and hold the up key for 3 seconds to enter the automatic search, and the Bluetooth on the display flash. After the connection is successful, the be white, and the characters of the two connected Bluetooth devices become larger, as shown in the figure below. Connect the aviation plug to the port with audio output. At this time, the headphone audio output, such as computers, , , mobile phones and other devices RX receiving mode: After turning on the device, it is in TX mode and press and hold the OK key for 3 seconds to switch to RX mode. Turn on Bluetooth on the phone and search for -02, click the Bluetooth name and connect. If the connection is successful, the display show the Bluetooth name of the mobile phone, as shown in Figure 2 below. Then insert the 3.5mm audio interface of the device into a device that can output sound, such as a speaker, TV, etc. Clear pairing list: When the Bluetooth transmitter is paired with the device, press and hold the up key for 3 seconds in both TX and RX modes to clear the pairing and disconnect from the current blue device. Colour:Black Material:ABS Package Contents: 1 x audio conversion adapter 1 x aircraft audio converter (Aircraft audio converter plug style is sent randomly, don't accept the specified) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.