Penn-Plax presents the Cascade 100 Hang-On Filter Replacement Media Cartridges. This 3-Pack of Cascade Poly Fiber Floss and Activated Carbon Media Cartridge is specially designed for Cascade 100 Power Hang-On Filters, allowing for simple and easy media replenishment. Safe for freshwater and saltwater aquariums. Double-Sided: Each media cartridge contains finely constructed Poly Fiber Floss at the front, and 1.2 ounces of research-grade Activated Carbon at the back. Furthermore, the internal rib structure evenly distributes Carbon throughout the cartridges for the most effective filtration. Clean & Healthy: These pieces trap floating particulate matter, remove harmful chemicals and toxins, clear up discolorations, and reduce foul odors from your aquarium's water. They help keep water inside your tank crystal clean. Measurements: 5.5” x 3.25” x 0.75” each. Shop Penn-Plax for All Your Pet's Needs: Penn-Plax is a manufacturer and distributor of top quality pet supplies, who specialize in creating excellent pet products for animals, both great and small.