Humidifier Filter for WF813 Relion (4 Pack) Aftermarket Product Sourced Exclusively by EFP - Exact Fit Parts High Quality Humidifier Wick Filter for Kaz WF-813 Approximate Measurements: 5-15/16" L x 3-15/16" W x 1-7/16" T Includes (4) Humidifier Filters as pictured