The Silicone Sine Wave Red Sport is made of pure silicone. Imprinted at our at our Energy Frequency. Designed give you that extra boost of energy like drinking an energy drink, good energy without the crash, like Red Bull on your Wrist. Available in five sizes: Extra small is 6.25 inches, great for children or women with smaller wrists. Small is 6.75 inches and is perfect for larger children and most women. Our medium is a good fit for most women and some men with a length of 7.5 inches. Large is 8 inches and will fit the majority of men. Our extra-large is 8.5 inches and is a good fit for the bigger wrist or small ankle.