MIFA F20 Bluetooth Speaker, Outdoor Portable Wireless Sport Speaker for Running Hiking Climbing Bicycling Camping Bluetooth 4.0 APP Control 1.BLUETOOTH 4.0 OR SD CARD : Portable Bluetooth Speakers Adopted Bluetooth 4.0 technology almost compatible to mostly bluetooth enabled devices. What's more, the SD Card option makes you do not need the device have bluetooth functions.The Special feature is that when you choose SD card mode to listen music ,your smartphone which paired with the speaker can show the playlist(the songs stored in SD card ) in the screen. 2.WEARABLE SPEAKER WIRELESS :Using a comfortable flexible wrist band ,the users can fix the speaker on the arm,and this speaker can track the steps and the calories burned when you are running ,and one button broadcasting the steps and time ,you don't need bring your smartphone and headset anymore when you run outside 3.RECHARGEABLE WIRELESS SPEAKER:Bulit-in 800mA li-on battery ,USB recharging,6 hours playtime 4.ONE BUTTON RECONNECT: Easy to set up, the pair mode MIFA-F20, just pairing in a while. And you can go almost 10M/33ft distance before the connection starts to go a bit fuzzy. No confusing buttons, everything is Simple as the speaker itself. 5.ELEGANT DESIGN:This speaker is small and light enough to take .There is no any burden when you run with speaker on the arm .