The headphones connect two mobile phones: The headphones can connect two mobile phones at the same time and share one set of headphones with friends without affecting each other. Excellent design: Ergonomic design, designed with 3 sizes of silicone ear plugs, sturdy and comfortable to wear. The 3000 mAh mini charging box is easy to carry and won?t get lost. Bluetooth specification: V5.0 Bluetooth range: 10 metres. Running time: 4 hours. Standby time: 150 hours. Charging time: 1 hour. Battery capacity: 40 mAh * 2 charging boxes: built-in 3000 mAh battery charging box charging time: 3-4 hours waterproof: IPX7 anti-sweat micro USB connection: can simultaneously charge phone and headphones. Tips [1] If you are using a Bluetooth headset for the first time, you need to charge it for 3-4 hours beforehand. When the battery is empty, the Bluetooth headset is not connected and affects the sound quality. [2] If the pairing of the left or right headphones does not work, the left and right headphones will work separately. It?s not a quality problem, please adjust the left and right headphones correctly. [3] The touchscreen area of the headphones is sensitive. To avoid errors, there should be a 3 second break before proceeding to the next step. WARNING: choking hazard - small parts. Not suitable for children under 3 years.