Upon closer inspection, there are some stains, but I think they are not very noticeable. Stain locations: Photo number Front: 6th photo, Neck: 7th photo, Sleeve: 8th photo, Back: 9th photo No stuff sack The following is a quote from the internet: High-quality down that achieves both "warmth" and "lightness" at a high level. Compared to general 550 fill power (FP) down, it exhibits stable heat retention even with a smaller amount of down. High-quality EX down The quality of down is indicated by the unit of fill power. The higher the number, the higher the quality, and generally, those with 600-700 fill power are considered good quality down, and those with 700 or more are considered high-quality down. "EX down," which achieves 800-1000 fill power, excels in bulkiness and stores a lot of warm air (dead air), ensuring extremely high heat retention with minimal weight. Single quilt construction A unique quilting pattern from the manufacturer that balances heat retention and lightness. It is a unique quilting pattern from the manufacturer that prevents cold spots and keeps you warm. It prevents the down from shifting, improves heat retention efficiency, and contributes to lightness and compactness. Material Features <Ballistic Nylon> The shell material that combines strength and lightness is Montbell's original Ballistic Nylon. This fiber is made by stretching nylon yarn during the spinning stage to give it strength, and when woven, it achieves about twice the tear strength compared to conventional nylon of the same weight. Anti-static processing to reduce unpleasant static electricity It is treated with anti-static processing to reduce static electricity. The effect does not diminish even after repeated washing and lasts semi-permanently.