Heat N Clean is an inside and outside kettle cleaner. It especially effective on the inside of kettles. When you have a lot of build up on the inside of your kettle, add a small amount of Heat N Clean with water, and bring to a boil, and dump out according to instructions. Does wonders for the inside of your popcorn kettle. Comes in a 31 oz. container. Easiest and safest kettle cleaning option.