The 3N1-20 sling backpack features a unique TST RIB structural protection for a D/SLR with battery pack & mid-range zoom lens attached as well as, 3-4 lenses, flash + personal gear. This unique bag provides ultimate freedom and allows for three carrying options in one while morphing from sling to backpack and back again fast and easy by use of its quick release buckles. In sling position, the bag easily swings around from back to front to achieve quick draw access to your main camera and backup lenses as well as fast and easy changing of lenses. In backpack position and "X" position you can comfortably carry your equipment for long distance walking when needed. The included chest belt and balancing hip strap helps take the load of your heavy equipment off your shoulders.