These heel cups are hypoallergenic non-toxic non-flammable and no odor great for heel ankle pain plantar fasciitis heel spur knee and back pain etc dual density heel cups providing maximum support and shock absorption using two levels medical grade silicone soft and firm washable and transferable will not get warmer than body temperature blue area is extra soft for greater cushioning of sensitive areas non allergenic and dermatologist tested providing flexibility and conforming to bony parts of the foot very useful for any prolonged standing or walking activity a must have for sporting activities especially where impact shock reduction is required provides amazing support and comfort to your feet all day long color: blue and transparent material: gel silicone