Active from Trion:Z takes water sports to the extreme! Active combines the negative-ion and magnet technology that has made Trion:Z products so popular among professional athletes with a waterproof silicone band to be the perfect combination for active sports enthusiasts. Colorful, stylish and comfortable, the Active is sure to be a hit among young and old alike. The twin-1000 gauss magnets in a patented Alternating North-South Polarity Orientation (ANSPO) provides increased magnetic field flow. It"s capsule of negative ion-producing minerals produces 50 to 100 times the negative ion power of competitors products. Energize your lifestyle with Active from Trion:Z. Small 17 cm (6.8") Medium 19 cm (7.6") Large 21 cm (8.4")