STRONG COMPATIBLE BLUETOOTH EARBUDS: Compatible with almost all Bluetooth enabled devices. LONG BATTERY LIFE : 4 -5 hours on a single earbud usage , takes 1-2 hours to fully charged. There is reminding sound when battery is low, and the led would flash in red at the same time. Led light turns blue when fully charged. Multifunction Button: 1. Answer key ( press 1 time )  2. Hang up key ( press 2 times )  3. Play button( press 1 time ) 4. Pause button ( press 1 time )  5.Switch machine key ( long press 5 seconds ) Frequency: 2.40 GHZ Transmission Distance: 12M