Features:Support BT connection playback, TF card playback, RCA input, and AUX input, meeting all your needs. Also supports FM Radio function.4*5W double horns provide full frequency range, surround sound, and the cinematic deep bass matched, bringing you high-quality music.Wireless BT transmission, stable and fast transmission, 10 meters of effective distance, great sound quality, restore music scene.Built-in 2000mAh large capacity battery, fast charging, long voyage, can be used continuously for about 3.5 hours.Supports TWS true wireless speaker function. 2 BS-28B speakers can connect to each other for stereo and powerful rich sound.True Wireless Speaker Connection Steps:1. Power on speaker 1, long press mode switching button for 3s then you can hear "ding" and the indicator light flashing quickly to enter BT mode.2. Power on speaker 2, long press mode switching button for 3s then you can hear "ding" and the indicator light flashing quickly to enter BT mode.3. Waiting for 2 speakers to connect automatically. The blue indicator light is always on after connect successfully. You will hear the voice prompt "The BT is connected successfully", and now the true wireless speaker function is available.4. Switch on the BT on your smartphone to pair with the speaker and then you can enjoy music now.5. The buttons on the speakers and remote control can control 2 speakers simultaneously.Specifications:Model Number: BS-28BBT Version: 4.0Output Power: 4 5W*4Channel: 2.0Frequency Response: 20-20KHzSNR: ≥80dbBattery: 3.7V 2000mAhWorking Time: about 3.5 hours (depends on music volume)Charging Voltage: 5V 1~2ATF Support: MP3Storage Type: TF max capacity does not exceed 32GBColor: BlackProduct Size: approx. 55*5.5*5cm/21.65*2.16*1.96inproduct Weight: 612g/21.58ozPackage Size: 59*8.7*8.5cm/23.22*3.42*3.34inPackage Weight: 875g/30.86ozPackage List:1 * BT Speaker1 * RCA Cable1 * USB Charging Cable1 * Remote Control1 * User Manual (English)