You could adjust or fold according to your head size, very fit for sport running, hiking, Jogging etc. Colorful and fashionable appearance, choose it and just match your current style.

Features:

• Bluetooth version: V4.2+EDR
• Bluetooth operating range : up to 10m (free space)
  
• Transmission frequency range: 2.4GHz-2.48GHz
  
• Supported profiles: A2DP, AVRCP, HSP, HFP
  
• Frequency response: 20Hz-20KHz
  
• Standby time: up to 100 hours
  
• Bluetooth music/call time: up to 5 hours
  
• Fully charged time: about 1-2 hours
  
• Operating environment: -10 to 50℃
  
• Charging voltage/current: DC 5V
  
• Battery Capacity: 400mAH