Girls Will Be Girls Strider Running Tank TopThis tank is so light, it's like wearing nothing at all. Ideal for hot summer training runs, it features reflective details and a soft polyester nylon blend fabric. Lightweight, breathable, anti bacterial, and anti UV, it packs heavy duty performance into an ultra light package. Fabrication: 80% nylon, 20% spandex Sizing note: These are designed to be a close fit tank, if you like more room, please size up.