In 2007, we began incorporating a removable hip belt on our Ultralight Backpacks. This feature allows a better fit for the user. This system also provides thru-hikers the ability to utilize two different size hip belts on those months-long, weight-shedding long distance hikes. A hiker could start out with a larger hip belt and then mail the smaller one to a mail drop up ahead on the trail when they feel they will have lost enough weight to justify the smaller belt. No more field sewing of the hip belt with floss to make it fit better! This belt fits pre 2012 Gorilla, Mariposa. It will also fit all G4 packs