Outdoor Cycling Bluetooth Mp3 Speaker Backpack Bag Stereo Music Amplifier BACKPACK WITH SPEAKER. This backpack speaker comes with 2 built-in bass resonating stereo subwoofer and multi compartments, ideal for outdoor sports like cycling, hiking, mountain climbing, travel, etc.high quality crystal clear sound, distinct mids and highs from our two precision acoustic drivers delivers excellent stereo sound and enhanced bass from our proprietary passive bass radiator design.It will really cool when you cycle, the music around you long time. CONNECT IN SECONDS to Bluetooth devices including: iPhone, iPad, iPod, Samsung, Kindle, Smartphones, Tablets; play audio from laptops, PCs, and non-Bluetooth devices using included 3.5mm audio cable/AUX-IN jack; includes Micro-USB charging cable.High speed wireless bluetooth 2.1 TF car etc. ERGONOMIC RUGGED DESIGN in the back, features with 360 degree breathable material, relax your pain and massage the muscle. HARD EVA MATERIAL, waterproof, anti-shock and pressure resistant.Comfortable to back. CONTROL PANEL,5 button design, Amplifier which in the control panel side. NEXT(volume up), PREVIOUS (volume down) play (pause, answer, hang up) and warning lights switch button. Press the light button, you can use at night, as the taillights.Buit-in 5200mAH polymer battery, 8-12 hours long continuously playback time.