Color : Swell SportFlex is a high-performance band made from durable and soft-touch silicone. It’s waterproof, dirtproof, sweatproof, and stainproof, with an adjustable closure system and ventilation details. No matter the sport, water activity, or competition, SportFlex is ready. With the launch of WHOOP 5.0, SportFlex will be available in new colors with an updated minimalist WHOOP brand mark on the hook. Plus, SportFlex comes with ECG indents for Medical Grade members. On your toughest days, SportFlex is the band you need.