I used it for three months with the cover on. "MUGON," a special pillow designed for side sleeping. The size is approximately 40 x 65 x 13 cm, and the materials are urethane foam (with charcoal) for the main body and a 100% polyester cover. It reduces the burden on the neck and shoulders even when sleeping on your side, ensuring an open airway for easy breathing and also helps with snoring.