Our most loved NANDEX ™  fabric (made famous by our 'Best Black Tights' or 'leggings' for our international customers), now available in Royal Navy. STAX. NANDEX ™ is the perfect combination of a buttery smooth, high-performance fabric that can support you through your work out and your everyday, stylish lifestyle. STAX. Classic Crop comes with removable padding and a fitted elastic waist band with a racer back design to provide medium support.