Tilos Rash guards are made from a blend recycled polyester and nylon which is not just eco friendly but also provides a very soft material that feels nice against the skin. It's also quick drying and also blocks 98% of harmful UV rays. These versatile rash guards can be worn on the beach or under your wetsuit. They are flat stitched so there's no chaffing and the material is lightweight and breathable so even dark colors wear cool.