The Blink Fresh Magic Bamboo Lime / Classic Blue / Pink Bouquet Scented Toilet Knocker provides a long-lasting fresh scent and prevents limescale build-up. Immediately ready to use. Very easy to use. How to use: Place the insert with the accessory in the basket and press until you hear a click. Hang it in the toilet bowl. When the cartridge is empty, simply pull it out and replace it with a refill cartridge