The beautifully designed Bottle Pack is terrific for walking or hiking. It's easy to put on and provides maximum accessibility, and even includes an amazingly large zippered storage compartment for your phone, iPod, keys, wallet, book, or even a small bottle for a child. It even has a reinforced headphone port! It is designed for any 32oz bottle, but nearly any size bottle will fit nicely. The shoulder sling is completely adjustable. Just the right size and so convenient!