The Glasfloss Z Line Series Yellow Pleated Filters Offer Improved Performance For Virtually Every Application. All Glasfloss Z Line Pleated Filters Feature Fibers Which Do Not Absorb Moisture And Will Not Support Microbial Growth. This Merv 11 Filter Provides High Performance with Low Pressure Drop For Energy Efficiency. The Glasfloss Z Line Series Filters Achieve A Merv 11 Rating.