20&rdquo; HBAG Sling Backpack Single Strap Shoulder Bag, Audio & Bottle Pocket, Black Size: 20.5 inch x 15 inch x 5 inch Made of light weight and water-resistant material One large main compartment is enough for books and binders (thick books or a basketball can easily fit in) One zippered mid pocket for accessories One side zippered pocket for wallet and media player such as mp3, CD player, keys, cellphone