UP Voltaic OffGrid Solar Backpacks Battery pack (included) stores power until you need it  great for outdoor enthusiasts. 4 watts of solar power for fast charging (1 hour in the sun = 3 hours of talk time). Up to 19 hours talk time or 48 hours music playback. Indicator light inside the logo shows when the panels are generating a charge. The Detachable Charging Section with straps and clips can be removed and attached to other bags or your bike Connect to Devices via 5 standard adapters (micro usb, mini usb, nokia, and 2 universals). Dedicated padded laptop pocket fits up to a 17" laptop. Wire channels throughout the bag for headphones, bladder tubes, etc. Adjustable phone/MP3 pouch on shoulder allows for easy access while charging. Removable waist strap, High density padding in shoulder straps and back and mesh backing material for better airflow. Shell made from recycled PET. Volume: 1500 cubic inches (25 liters)&lt;br /&gt; Dimensions: 18 inches high x 16 inches wide x 8 inches deep (46cm x 40cm x 21cm)