TWS wireless headphones are a type of headphones that connect without a cable not only to the playback device, but also to each other. They allow you to wirelessly listen to music, answer phone calls. The headphones are small, comfortable and reliable. The functions of the headphones are controlled using the function buttons. The headphone case has a built-in 300mAh battery that allows you to recharge the headphones while traveling, training or walking. Bluetooth version: v.5.0. Supported Bluetooth profiles: HSP HFP, A2DP and AVRCP. Bluetooth transmitter power: 3dBm Bluetooth transmitter frequency: 2.402-2.480GHz Range: up to 10 meters. Built-in rechargeable Li-Poly battery: headphones: 40mAh charging case: 300mAh Usage time (talk time): up to 4 hours Music playback time: up to 3 hours Charging time: about 1 hour Frequency response: 20Hz-20,000Hz Input (charging) voltage: DC 5V The set includes a 25cm microUSB charging cable