The Hydro Flask 15 pack Cleaning Tablets are made to melt away that gross brown film you can't quite seem to scrub off the inside of your container. They clean sports bottles and plastic too, taking off built up electrolyte mix or the smell of whatever else you put in those things. They're made with all natural ingredients and easy to use. Simply pop one in with some warm water, ignore for a while, and BOOM! It's a whole new Hydro.