The THUNDER T23 from ZIZO packs a powerful 16W punch with high definition sound and a long lasting 1500 mAh built-in rechargeable battery. Bluetooth capabilities along with True Wireless pairing technology create an out of this world stereo sound experience.The ZIZO THUNDER T23 is backed by a ZIZO one year warranty. Specifications: Bluetooth version: V5.1 Speaker Size: 2 inch*2 RMS power output: 8W, 4Ω Peak power output: 16W, 4Ω Battery Capacity: 3.7V, 1500mAh Play time: 3 hours at maximum volume & 7 hours at 50% volume Frequency Response: 80HZ-20KHZ Bluetooth connecting range: 10m