• Upgraded: You can use the bag as a power bank now!!! And the battery capacity has been increased from 1000mAh to 2000mAh!: Dry bags Built in Wireless Bluetooth Speaker: Not like other common waterproof dry bag, the roll top waterproof bag has integrated a Bluetooth speaker, compatible with all android and IOS mobile phones. Hiking with waterproof bag and enjoying music at the same time, you will never feel bored.