I ordered this bag to combat my constant back pain and shoulder pain.  This is not a small bag.  It's the perfect size to fit what you would put into a normal sized purse.  Cell phone, keys, the basics.  If you want to pack a notebook or a tablet then you want the small.  For me it's perfect and since I have started using it my back and shoulder pain has gotten so much better.  Easy to clean, lots of pockets.  Will buy again whenever this one needs replacing.