The knee supports contain 12 strategically placed magnets around the hole at the centre of the knee support, which improve circulation, thus speeding the process of healing aching muscles and joints. They are made of the highest grade neoprene, covered with stretch nylon on both sides for compression and heat retention, which also helps blood circulation and reduces any further swelling. There are adjustable Velcro straps ensuring a comfortable fit and stabilization to prevent further injury, whilst also making the support easier to put on and remove. Neoprene is a stretchable, flexible and comfortable material that holds heat in but lets moisture (sweat) out. You will feel the effect as the support relieves muscular tension and fatigue through the increased blood circulation.