KAKU KSC-447 Wireless / Bluetooth 5.0 Sport Headsets / Black

Kaku Wireless Headphones User manual : Power on: press 2 seconds.  Power off: press 3 seconds .  Answer / Hang Up: Click once .  Reject: press 2 seconds .  Previous song: Long press the "-" button.  Next song: hold down the "+" button.  Volume Up / Down: Short press "+" button, short press "-" button. Specifications : Bluetooth version: Bluetooth 5.0. Battery capacity: 55  mAh .  Working Time: about 4 hours .  Standby time: 120 hours .  Tube diameter: 10 (mm) .  Speaker impedance: 16 .  Sensitivity: 99 ~ 3 dB / mw (dB) .  Speaker power:  3-5 MW . Beautiful packaging, excellent quality. Good quality materials