REMAX RB-S20 Bluetooth 4.2 Rotatable Ear Shell Rear-mounted Bluetooth Sports Earphone 1. Bluetooth 4.2 chip, barrier-free transmission up to 10 meters, lossless transmission of sound source, memory recognition paired devices, intelligent quick connection, more convenient to use. 2. The composite diaphragm sounding unit is matched with the original cavity design of the earphone, so that the earphone is rich in the sense of hearing, the medium and high frequency is bright and smooth, and the low frequency dive is powerful. 3. 30 degree adjustable rotating ear shell to meet the auricle of different people, oblique ear tube design, comfortable fit ear canal. 4. Buffer earloop design, PP+TPE material, long-wearing without pressure. 5. It adopts TPE environmentally friendly material and is worn according to ergonomic design. It is light and comfortable to wear. 6. Can prevent sweat from damaging the device. Product specifications: 1. Weight: 20.4g 2. Bluetooth version: 4.2. 3. Transmission distance: 10m for obstacles. 4. Frequency response: 20-20KHz. 5. Output sensitivity: 86dB +- 3dB. 6. Microphone sensitivity: -42dB+-3dB. 7. Battery capacity: 65mAh. 8. Rated power: 3mW. 9. Drive unit: 10mm. 10. Play time: about 3.5 hours. 11. Standby time: about 60 hours. 12. Charging time: about 1 hour. 13. Support function: support pauseplay, previousnext song, turn updown volume, connecthang up call, drag 2, battery power display, end number redial, voice prompt.