The boy's KILPI NATHANIEL- JB thermo set is made of a functional, very pleasant material called OPTI-DRY. It is fast drying and reliably evaporates moisture and sweat in a short period of time. The set fits perfectly on the body and adapts to all movement. It is seamless, stretchy and very comfortable. It will find a way to be a part of all your sport and outdoor activities. Material: 90% Polyamide, 8% Elastane, 2% Polyester