Fits Sunsun HW-304 HW-404 HW-704 HW-3000 canister filters Filter media pads evenly soak with water to successfully trap unwanted particles. Porous surface traps toxins, allowing them to decompose. Capable of catching both large and small dirt pieces, helping to keep your tank clean. Pads may be re-used multiple times, making for an economical solution to your filtration needs. Easy to clean—simply rinse and lightly squeeze. Replaced after 6-12 months due to micro holes of sponge will gradually clog by debris