VICTORSTAR@ Waterproof Sport Speaker /Bluetooth CSR 4.0 with NFC /3600mah Rechargeable Battery 12 Playing Hours /2x3W Stereo Bass Sound /Shockproof / Anti-scratch /Portable Power Bank (Red) 1. NFC (near field communication) Function & Bluetooth speaker 4.0 and CSR chipset connects faster, more stable, compatible with all your Bluetooth-equipped devices, and Outstanding connection range of up to 10 meters . 2. Built-in microphone: Enables use this Wireless Bluetooth Speaker as a speakerphone, so you can enjoy hands-free calling . 3. Built-in rechargeable 3.7V, 3600 mAh lithium-ion polymer battery: Provides extended playback, enables you to stream music for up to 12 hours on a full charge . 4, A standard USB jack can be used as a power bank, that you can charge your phone and other device while you are enjoying the music . 5. The soft and thick silicon shell for better protection again shock and scretch . Water-proof and sand-proof design Safeguards the subwoofer sound speakers against water submersion, so you can use the speaker both indoors and outdoors .