Nix-branded Patch Refills are the disposable consumable to pair with the reusable Nix Hydration Biosensor pod before each new workout. Each patch, just under 7 cm in diameter, is applied to the bicep using latex-free medical-grade adhesive, in a completely non-invasive way. Recommended for sweat-inducing workouts, such as running or cycling, lasting at least 45 minutes: afterwards, the Nix app provides a useful summary for building a more conscious hydration strategy over time. Pack of 4 disposable patches.