Features: 1. With ergonomic design and environmentally friendly TPU , it is comfortable and easy to wear. 2. Keep it at a comfortable temperature for the human body, without causing thermal burns, for 2-3 hours of warm experience. 3. High-strength polyurethane is not easy to break, suitable for children, adults, etc. to use in cold winter. 4. Soak it in 80-100 degree hot water for about 8-10 minutes, make it melt, and wear it, and the is . 5. The design that fits the neck and is not easy to fall off, is suitable for commuting to work, school, outdoor , camping, and other scenes. Specification: PCM Size L Inner diameter: About 120mm 4.72 inch Outer diameter: About 160×200mm 6.3 7.8inch Weight: About 150g size Inner diameter: About 110mm 4.33 inch Outer diameter: About 145×185mm 5.7 7.3inch Weight: About 120g Size S Inner diameter: About 95mm 3.74 inch Outer diameter: About130×150mm 5.9inch Weight: About 100g Product List: Heating collar 1 Notes: 1. Due to the different monitor and light effect, the actual color of the item might be slightly different from the color which is showed in the pictures. 2. Please forgive a slight measuring deviation due to manual measurement.?Perfect Gift: This stylish and practical neck warmer is perfect as a birthday, Christmas, Mother's Day, Father's Day, or Valentine's Day gift for family, friends, or loved . ?Various Occasions: The heater design of this heater fits the neck and is not easy to fall off, suitable for commuting to work, school, outdoor , camping, and other scenarios. ?Reusable Design: This necklace adopts a physical heating design, which achieves a rapid heating effect by immersing in boiling water. It is easy to operate and can be recycled. ?Neck Warmth: 48 is a comfortable temperature for the human body, this self-heating neck collar can provide you with 1-2 hours of warm experience in cold weather. ?Thickened Material: The heating collar is made of high-density PCM material, which is resistant to high temperature and not easy to break, suitable for use in cold winter.