▪ MERV 13 ▪ High Efficiency With Low Initial Resistance ▪ Moisture Resistant ▪ 100% Synthetic Recyclable ▪ High Loft Media ▪ 2 Piece Heavy-Duty Die Cut Frame ▪ Expanded Metal Backing ▪ Double Wall Frame ▪ Diagonal Grid Supports For Maximum Strength ▪ Can Be Used As Prefilters To Extend The Life Of Higher Efficiency Filters Or Use On Their Own ▪ Suitable For Commercial And Industrial Application ▪ UL Standard 900 Classified ▪ "Box Of 12"