Oust Kettle Descaler Drop-In Bag Regular boiling can take its toll on a kettle and cause limescale, affecting its performance and boiling time. The Oust Kettle Descaler Drop-in-Bag is the quick, convenient way to restore kettles to their best in just 10 minutes. Simply drop the bag in the kettle and let the formula work its magic. **Please note that this product contains an irritant substance and great care should be taken when using the product. Please do not use for anything other than the original intended use.**