The Grreat Choice Filter Cartridge has activated carbons to remove chemical impurities, while floss traps debris. Fits Grreat Choice 30/40 Internal Power Filter. Only at PetSmart.Features: Traps debris
Includes:

• 3 – Filter Cartridges
  Dimensions: 3.5 in x 6.4 in (8.890 cm x 16.256 cm)
  Caution: This is not a toy. Keep out of reach of children.

Instructions:
1. Rinse the filter cartridge under cool tap water to remove dust.
2. Insert the filter cartridge into the cartridge housing. Make sure the cartridge housing, with filter cartridge, fits completely into the filter housing.
3. Change the filter cartridge every 3 – 4 weeks or as often as needed.
4. Remove the filter cartridge when medicating the water as the carbon will absorb the medication.