About The Ruark Audio BackPack 3 The Ruark Audio BackPack 3 transforms your R1/R1S tabletop radio or MR1 wireless speakers into completely portable products. A battery pack that attaches to the back of either model so you can enjoy rich quality sound wherever you please. It frees these miniature marvels from the mains power socket and into the bathroom or onto the decking and the great outdoors. Placing batteries inside takes valuable speaker capacity which can result in unrefined sound, but BackPack 3 allows R1/R1S and MR1 to retain their rich mains powered performance, but with complete portability. A total evolution of the original, BackPack 3 attaches seamlessly to R1/R1S and MR1 and once fitted can be left permanently in place as it charges automatically whenever the music systems are connected to a mains power supply. A full charge will deliver up to twelve hours of mains free listening depending on volume. Main Features & Specifications Manufacturer: Ruark Audio Package Contents: Battery Pack And 2 x Screws Battery Rechargeable: Yes Height: 90mm Battery Chemistry: Lithium Ion (Li-Ion) Width: 106mm Depth: 21mm Output Voltage: 14 V DC Maximum Battery Run Time: 12 Hour Maximum Battery Recharge Time: 5 Hour Weight (Approximate): 230 g Note: Features and Specifications Subject To Change Without Notice. E&OE.