I-Venstar Waterproof Bluetooth Speaker, 4400mah Battery Power Bank, Portable Wireless Dustproof Anti-scratch Shockproof Subwoofer Bass Sound Sport Speaker with 2x3W / CSR Chipset / NFC Technology / Mic for Camping Hiking Bathing Biking Cycling Running Climbing Indoor Outdoor The rechargeable, high capacity 4400mAh polymer Li-ion battery allows for an extended power bank that will charge your phone or other device. Prior to use the speaker, it is recommended to fully charge. NFC technology (near field communication) allows easier Bluetooth operation. One-touch pairing by simply tapping your NFC-enabled bluetooth smart device on the speaker, bring more intelligent, convenient, comfortable life. Bluetooth 4.0 and CSR chipset connects faster, more stable, compatible with all your Bluetooth-equipped devices, an excellent Bluetooth range about 30 feet. Waterproof, dustproof, anti-scratch, shockproof. Metal and silicone housing design make it anti-skid. Waterproof features allow you to enjoy music when bathing. But totally immersed into water is not supported by far. Metal Hook Loop idea for easy attachment while outdoor sport, camping, hiking, biking, etc.