Pet Water Fountain Filter FTE-P34 Material: Microfilter Cotton, Coconut Shell, Activated Carbon, Ion Exchange Resin Size: 13 × 8 × 0.8 cm / 3 pieces Usage and Instructions: It is recommended to replace the filter cotton every 2-4 weeks. Please soak and wash the filter cotton in water for 5-10 minutes before use. Only for use with P3 and P4 series.