L size Inner diameter 12cm, thickness approximately 2cm, inner circumference approximately 38cm. Neck size guide: 30-39cm This cool neck ring can be used simply by putting it around your neck. Also, the carotid artery is located in the neck, and cooling this area can cool the blood flowing throughout the body, effectively cooling the whole body and preventing heatstroke. Cooling duration: 15-20 minutes in the freezer or refrigerator, about 20 minutes in ice water or cold water! Usable for 60-120 minutes based on an outside temperature of 25-40℃. ✨Brand new, unused✨ *Please understand that this item is stored at home and will be shipped in simple packaging. *Instant purchase OK! Purchase without comment OK! *Free shipping *Feel free to comment! #Click here for naonao's product list ✨☜ -------------------------------------------------- 28℃ Cool Ring Cool Band Neck Cooler Ice Neck Ring Running Instant Cooling Cooling Ring Neck Ring Cooling Cool Refreshing Heatstroke Prevention Cooling Goods Neck Hanging Cooling