Mediabridge Forte Portable Bluetooth Speaker with Powered Rear-Firing Subwoofer - Wireless Speaker with Rechargeable Battery - (Part# BTS-1B) Powerful Dual Driver Design: 44mm acoustic driver with rear firing 38mm powered subwoofer combine for 5 Watts of full bodied power with deep bass that belies small, portable bluetooth speakers. Up to 6 hours of music from rechargeable lithium-ion battery. Recharges via standard micro USB cables and standard USB chargers. Compact design is 3.5 inches tall x 2.5 inches wide x 2.5 inches deep and weighs in at a portable 8 ounces. Easy to use with any smartphone, tablet or MP3 player. Wirelessly stream voice calls, audio or music via Bluetooth v3.0 +EDR or plug into the 3.5mm aux port. Accept/End phone calls and use Siri or Google Now with built-in microphone.