The Protactic has everything I need for my main backpack. What sets it apart is the Molle-compliant webbing on top, which allow me to attach light, soft pouches for clothes etc. that doesn't need protection (e.g. Mil-Tec, Gondor, ask from your local Airsoft, paintball or army gear stores). It complies with airline standards, so I can always bring it up and not have to risk my gear. It's the bag that expands to every need, from a day bag to a 3-day hiking bag.