Product Description The Glasfloss Z-Line Series pleated filters offer improved performance for virtually every application. The mechanical structure of the media fibers sustains efficiency over the service life of the filter and produces high dust-holding capacity. All Glasfloss Z-Line pleated filters feature fibers which do not absorb moisture and will not support microbial growth. The Glasfloss Z-Line Series ZL filters achieve a MERV 10 per the ANSI/ASHRAE 52.2-2012 Supplement Standard. From the Manufacturer The Glasfloss Z-Line Series pleated filters offer improved performance for virtually every application. The mechanical structure of the media fibers sustains efficiency over the service life of the filter and produces high dust-holding capacity. All Glasfloss Z-Line pleated filters feature fibers which do not absorb moisture and will not support microbial growth. The Glasfloss Z-Line Series ZL filters achieve a MERV 8 per the ANSI/ASHRAE 52.2-2007 Test Standard.