Unique butterfly shape provides knee & leg support. The central airflow hole design is better to increase air circulation and keep cooling all night. Using a leg pillow for sleeping helps relieve knee pain and promote better sleep. The cooling ice silk cover of the knee pillow is breathable & machine washable. The elastic strap is freely stretched to hold the thigh pillow between your legs. The butterfly shape perfectly fits the body type and different sleeping positions. Putting the knee pillow with strap between your legs while sleeping can help to align your spine, reducing the pressure on your joints. Using the leg pillow can also improve blood circulation and reduce swelling.