For on-the-go storage, try the Under Armour Essentials Sackpack for women. This bag has an expandable construction for all the space you need. It has Storm technology that repels water, fleece-lined pocket with zipper front panel and a strapping system that opens to a main compartment.
Dimensions: 17" x 7.2" x 15.4"
UA Storm technology repels water
Fleece-lined pocket with full-length zipper on front
Strapping system opens to the zippered main compartment