Describe 5/7/9 Length: 47cm Product functions and features include: 1. Self-heating function: Made of special materials, it can generate heat when exposed to effectively relieving neck pain and discomfort. 2. Soothe neck muscles: Hot compress can promote blood circulation in the neck, relieve muscle tension, and relieve neck fatigue. 3. Comfortable and soft: The soft and comfortable fabric material fits the curve of the neck, making it comfortable to wear and less likely to cause discomfort. 4. Convenient to use: With an adjustable design, the tightness can be adjusted according to the size of the individual's neck, making it easy to use and carry. 5. Multifunctional function: In addition to relieving neck discomfort, it can also be used for various purposes such as keeping warm and preventing neck injuries. How to use: Relieve neck pain and muscle tension. Promote blood circulation in the neck and increase metabolism in the neck. Improve neck joint mobility and reduce the risk of cervical spondylosis. Prevent discomfort caused by cold neck and improve neck resistance. Improve neck muscle relaxation, reduce neck fatigue, and improve work and life quality. Package includes: Self-heating neck brace*1