Active Duck Discs contains a gel-based formula that adheres to the toilet bowl to keep it clean and fresh. The active discs prevent the accumulation of limescale and stains, eliminating germs and leaving a pleasant fragrance. Unique gel technology with 360-degree coverage. No plastic support required. Hygienically cleans with each flush. Up to 700 flushes per refill. Keeps the toilet clean and fresh for up to 6 weeks. Suitable for septic tanks.