I only used it once as a test. Just by lying down for 8 minutes a day, it aligns the cervical spine to its correct position. It can be expected to improve stiff shoulders and straight neck through relaxation and acupressure effects on the cervical spine. It's a reversible design that allows you to adjust the intensity of the stretching effect depending on the direction you use it. Made of resin, it's lightweight and convenient to carry, and can be washed with water for hygienic use. How to use: Method 1: Place the product flat, lie down, and then naturally relax your neck, using the weight of your head for a massage stretch. Method 2: Fix the product in the correct posture, lie down, and then shake your neck from side to side to get the effect of a neck muscle massage.