Product Overview: The WHOOP HydroKnit Band 4.0 is designed for high-performance use in wet and humid environments, offering both comfort and durability for WHOOP 4.0 users during intense activities. Key Features: ‣ HydroKnit fabric optimized for water resistance and quick drying ‣ Breathable, durable material designed for active use ‣ Adjustable, secure fit for continuous wear in all conditions Technical Specifications: ‣ Material: 92% Recycled Polyester, 8% Elastane, Stainless Steel ‣ Compatibility: Compatible with WHOOP 4.0 fitness tracker ‣ Length: 9.5 in/24 cm.