Mashable – WHOOP is pro sports' favorite wearable. After training with it, I can see why.

WHOOP is clearly different than other fitness trackers right out of the box. The minimalist waterproof strap has no screen or display, and the basic nylon band, which is made of what the company calls “nanostretch material,” is stretchy and less sturdy than silicone offerings from the likes of Fitbit and Garmin.