Bluetooth speaker features: Aluminum alloy shell Unique light coil design, playing status smart reminder With special intelligent voice navigation function Auxiliary input, support connecting with many kinds external audio sources External volume adjustment buttons Supporting tf card interface to play mp3, wav and ape/flac clear lossless audio formats Handsfree function when coming call received Line in Nfc function (on option) Product parameters: Output: 3w Bluetooth standard: v2.1+edr Speaker: 50mm Built-in battery: 3.7v 500mah Input voltage: dc 5v Charging time: 2 hours Playing time: 6 - 8 hours Impedance for speaker: 4¦¸ Thd:¡Ü1% (1khz/1w) Snr: >90db Frequency response:90hz to 18khz Reception distance: ¡Ý10m Material: aluminum alloy shell Dimension: 60(¦µ)x58(h)mm Unit weight: 145g