Cowin FOX Portable Outdoor Bluetooth Speaker - Green Powerful sound. One big driver and one big passive radiators provide big voice, powerful enough for badminton, BBQ, picnic and other outdoor activities. Ultra-portable. It's a elegant piece of audio equipment that can haul around in a backpack or a cooler. Durability. FOX is sturdy and capable of withstanding daily use, include frequent movement and plugging and unplugging. TF card function. Aux input enables you to connet to other audio sources, like a tablet or MP3 player. Built-in speakerphone lets you take calls out loud and clear.