Purchased from an authorized retailer and is unused. The features, despite being UL-oriented, include an air mesh back and removable pads with three-dimensional irregularities and air holes, which I believe is designed to prevent sweatiness on the back. It's a large 40L capacity, but I think the wide shoulder straps, typical of trail running packs, are designed to reduce shoulder pain. Also, the hip belt helps prevent side-to-side movement. I've purchased this item once, so please refrain from purchasing if you are overly concerned about details. The following is a product description: "FAST PACK 40" is a large-capacity pack that enables light and comfortable movement in the field. The lightweight "FAST PACK 40" is ideal for long hours of activity and activities where you enjoy carrying a lot of luggage in nature. Features: * The large front storage on the chest strap can store drinks, smartphones, maps, sunglasses, energy supplements, and other equipment. You can take them out without taking off the pack. * Full side zippers allow quick and easy access to the contents. * The back panel features the new "INFIKNIT™ + FASTFLOW," which reduces the impact from the contents and prevents you from feeling the weight, and the part that touches the back is equipped with soft cushioning. It is three-dimensional and breathable, making long hours of activity comfortable. (Panel is removable) * Waist belt included (removable) * Trekking pole attachment included * Easy-access pocket with key clip in the internal pocket * Large external stretch mesh pocket for quick access * Two large side pockets that can hold large water bottles * Capacity: 40 L * Weight: 709g * Height/Width/Length: 49.5 cm / 27.9 cm / 19.7 cm * Materials: Monorip Mesh, Nylon ACE Rip (STS coating), Multi-Stretch Mesh (durable/water-resistant) * Ice axe attachment loop included * Whistle included * Front pocket for mobile phone included * Reservoir compatible