Features: Made of premium ABS material, wear resistant and durable. Small size, hidden design, easy to carry. With stereo sound effect to enjoy pure music. Support multi-point connection and hands-free calls. Lightweight, comfortable to wear. Smart noise reduction and sound notification. Description: Bluetooth version: 4.1 Output Power of Power Amplifier: RMS 2*18MW (THD=10%) Signal to Noise Ratio of Power Amplifier: ≥90dB Input voltage: 3.7V Battery: Built-in Li-on rechargeable battery Playing time: 1-2.5 hours Talking time: 4 hours Charging time: 1-2 hours Charging input voltage: DC5V 500MAH Speaker: 2*16Ω 20MW Φ10mm Range of frequency response: 20Hz-20KHz Sensitivity: ≥100dB + 2dB SNR: 80Db transmission / receiver frequency: 2.4-2.48GHz Distance: no obstacle of 10 meters Specifications: Model: 530X Material: ABS Color: black, white, blue, pink, skin color Size: 20*20*30mm Package Included: 1 x Headphone 1 x USB Cable 1 x User Manual Notes: 1. Due to the difference between different monitors, the picture may not reflect the actual color of the item. We guarantee the style is the same as shown in the pictures. 2. Due to different personal measuring techniques, there might be 1-7cm error of the physical. Thank you!