The Lowepro Flipside Trek BP 450 AW is a mid-sized backpack with an unfussy look and a secure equipment opening that faces your back, so it can't be opened when you're wearing it. Seems awkward at first, except you generally need to take off your pack to access your gear anyway, and this way no one can unzip your pack and run off with your goodies while it's on your back. Rugged and well made, with a built-in waterproof cover for harsh weather. In near-new condition. Interior dimensions are approximately 16x24x32cm.