Main Features:MARROW 303B wireless Bluetooth 4.0 music headphonesAdopts chipset, work more smoothlyHiFi quality, delivers a clear and delicate soundPowerful bass music effect, excellent listening experienceErgonomic design, feel no fatigue after a long time wearingProtein leather material, ultra-soft earmuff, super comfortable to wearBuilt-in 450mAh rechargeable Li-polymer battery, up to 20h working timeLightweight and portable to carry out Brand: MARROW Model: 303B Color: Black,Blue,White Wearing type: Headband Function: Answering Phone,Bluetooth,HiFi,Microphone,Song Switching Connectivity : Wireless Connecting interface: Micro USB Application: Mobile phone,Portable Media Player,Sport Driver unit: 40mm Frequency response: 20-20000Hz Impedance: 32ohms SNR: 80dB Sensitivity: 106db Talk time: 20h Music Time: 15h Standby time: 135h Charging Time (h): 3h Bluetooth: Yes Bluetooth version: V4.0 Bluetooth distance: W/O obstacles 10m Bluetooth protocol: A2DP,AVRCP,HFP,HSP Bluetooth mode: Hands free Battery Capacity(mAh): 450mAh 0.486 Package weight: 0.53716 kg Product size (L x W x H): 16.00 x 19.00 x 3.00 cm / 6.3 x 7.48 x 1.18 inches Package size (L x W x H): 21.50 x 23.00 x 6.10 cm / 8.46 x 9.06 x 2.4 inches Package Contents: 1 x Headphones, 1 x USB Cable