Penn Plax Filt-a-Carb Universal Carbon Undergravel Filter Cartridge helps keep your aquarium water clean. Fits most undergravel filters. Contains quality activated carbon that removes harmful gases and odors and clears up discolorations. Quick easy and disposable.

• Helps keep tank water healthy
• Trouble-free maintenance
• Ready to use
• Clears up unsightly discoloration

Instructions: Rinse thoroughly before placing in filter. For best results, replace every 2-4 weeks.