Our Long Johns provide soothing warmth that may relieve groin, superficial hip, and leg muscle discomfort. How do they accomplish this? With Back on Track’s specially designed ceramic-infused Welltex fabric. The ceramic powder reflects your own body heat and creates a soothing far infrared thermal warmth. Heat therapy is a well-recognized method used for healing injured muscles, joints, and tendons. Our Long Johns’ fabric is ribbed, and comfortable. Many people wear our Long Johns just to stay warm. https://botcanada.com/ sizing charts can be found https://botcanada.com/sizing-charts/