Audio:Maximum Sound Level: 85dBA. Frequency Range: 108Hz - 20kHz. Drivers: One 2" driver and Two ¾" tweeters. Waterproof: IPX7 rated: UE ROLL can be immersed in liquid up to 1m for up to 30 minutes. Compatibility: For Audio Playback - Smartphones, tablets and other devices that support Bluetooth wireless audio profile [Advanced Audio Distribution Profile (A2DP)] or 3.5 mm audio output. Wireless Capabilities:Pair up to 8 Bluetooth enabled devices - Connect up to two source devices at the same time. Wirelessly play (stream) to 2 UE ROLLs from one source. Mobile range of play is up to 20m or (65ft). Power:Rechargeable Lithium-Ion Battery for up to 9 hours of battery life between Micro USB charges. Actual battery life will vary with use, settings and environmental conditions. Charge time: 5.5 hours.