15x11in Primary Replacement Air Filter for XL300 Fume ExtractorsXL 300 REPLACEMENT FILTER: This box prefilter is the exact replacement primary filter for OMTech's industrial strength series XL 300 fume extractors; for optimal filtration, choose only original OMTech filters for your machine! HIGH EFFICIENCY: Our 15x11x4 inch air purifier box filter rids the air of 99% of unwanted substances that are 50 microns in size or larger such as dust, debris, and other airborne particles, providing coarse but effective