Explorer-SP combines advanced sound and functionality for a superb audio experience at home or away. Its 3D sound feature provides enhanced depth to your music and its acoustic bass port delivers rich, deep notes to compliment the 3D width. 3D sound for increased width and depth to your music Extended frequency response for enhanced acoustics 140hz-18khz Bass port for full rich sound Powered by rechargeable lithium-ion battery or mains 8-hour battery life with 2 hour fast charge Battery level indicator *This product is Recertified. A recertified product is one that is returned by a customer, for whatever reason, and then restored to original working condition after undergoing an intensive inspection process by qualified technicians. The recertified product is then offered at a substantially discounted price. All stock of our current products are guaranteed to be in working condition and have been successfully tested for optimal performance. 7 day return policy is in effect for both in-store and online purchases. See in store for more details.