I purchased and opened it, but it was never used and has been stored at home. The bag has some scratches. Size: S For those with a shoulder blade width of 40cm or less. - Function: Positional change cushion - Features: Lightweight and without burden - Uses: Sleep, snoring prevention, posture correction Supports side sleeping - This backpack provides comfortable back support that supports side sleeping, preventing the tongue, soft palate, and loose throat tissues from falling backward and blocking the airway. Therefore, it can reduce snoring caused solely by throat problems. You can develop the habit of side sleeping with a 2-month backpack training program. Large enough to maintain a side sleeping position during sleep - This backpack is large enough to maintain a side sleeping position without your back touching. If it's not the right size or if you lie flat, it can compress your spine and cause you to sleep on your back. This can cause pain and be dangerous. Stability and comfort at night - This backpack has a three-point fixation design on both shoulders and waist, distributing the pressure of the fixing straps and ensuring comfortable and stable support. If you only fix it to your chest with one strap (especially for women) or put it in the back pocket of your pajamas, it can shift and slip over time, allowing you to end up on your back. Please purchase if you understand that this is a home-stored item. Price reduced.