The Air Necklace is an ultra-light version of Phiten’s trademark necklace, conceptualized and tested by world-class marathon runners asking for something lighter to reduce necklace bounce. The Titanium Silica Foam Core cuts overall weight and is formulated specifically for those times when every ounce counts. The fabric shell is a mixture of highly elastic polyurethane and nylon, which allows for a claspless design that stretches effortlessly over the head. Features: - Ultra-Light Design: The Air Necklace is an ultra-light version of Phiten's renowned necklace, designed and tested by marathon runners. It was developed to reduce necklace bounce during intense activities.- Titanium Silica Foam Core: Featuring a Titanium Silica Foam Core, this necklace effectively reduces overall weight, making it ideal for situations where every ounce counts.- Claspless and Stretchable: The necklace boasts a fabric shell made of a blend of highly elastic polyurethane and nylon. This unique design eliminates the need for a clasp, allowing for easy stretching over the head for effortless wear. Material:Outer - Nylon and PolyurethaneInner - Silicone and SilicaTechnology:AQUA-TITANIUM®Made in Japan