The Ameribag Healthy Back Bag hugs the natural curve of your back, distributing the weight ergonomically across the spine, making this the most comfortable bag you will ever use. Intelligent pockets inside and out keep you organized and balance the weight. All this reduces stress on your neck, shoulder and back, and actually makes your load feel lighter. See photos for measurements. This is the large bag, nylon and a denim or periwinkle blue in color.