No scrubbing required! Simply scoop this magic powder (using the scoop provided) into your toilet, along with boiling water, and watch it go to work! The moment it hits the water, it starts to fizz, foaming up, to clean right under the rim, without spilling over. No need for scrubbing. When the foam dissolves, simply flush for a clean, limescale-free bowl. WC Powder needs boiling water to work. 480g tub.