Callaway Sport Series Bracelet These Hypo allergenic Silicone Bracelets and Necklaces utilize Ionetix Technology which features negative ion elements in their construction. These materials have been used by the world's best athletes in many sports including Baseball, Biking, and Golf. The Sport Series is perfect for active people because they are specifically designed for athletic activity. These silicon based bracelets and necklaces feature an Ionetix strip which contains minus ion attracting titanium. Bracelet Hex Lock System Adjustable one size fits all