New in box From website: The HydroKnit band is a sleek, fast-drying fabrication that’s a fan favorite for a reason. It dries twice as fast as SuperKnit and retains 30% less water – making it a must-have for water sports, high-sweat activities, or just taking a shower. A portion of the proceeds from the Hydroknit Collection will go toward the Michael Phelps Foundation (MPF) to promote water safety. Since its founding in 2008 and with the help of strategic partnerships, MPF has provided critical, live-saving programming to more than 350,000 people worldwide. Includes Band, Hook, Clasp, and Fast Link™ slider that makes swapping bands easier than ever. Only compatible with WHOOP® 4.0.