WK Bluetooth Headphones Youpin Series TWS V4 White Small size & powerful Automatic pairing, connecting when opening the pop-up window One-key operation, easy to use The all-metal cavity structure effectively isolates environmental noise Touch control operation, call and listen to the song with your heart Down to 0 latency, smoother playBluetooth Version: V5.1 Material:ABS+PC+Silicone Charging box: 200mAh Earphone:2*30mAh Charging: 1 hour Play: about 4 hours Charging box: 200mAh Standby time: 40 days Frequency responce : 20Hz-20kHz 13mm loudspeaker