Speedo Mens Boys River and Tides PowerPLUS Brief Active Swimsuit Trunk 79% Nylon / 21% Xtra Life Lycra Fiber Speedo's PowerPLUS fabric brings added power, comfort and fluidity of motion PowerPlus fabric cuts weight and drag Up to 50% lighter than traditional performance swimwear 79% Nylon / 21% Xtra Life Lycra Fiber PowerPLUS also resists pilling, fits perfectly and retains its shape use after use