Comparing to the 3M filters I'd been using: Thinner by close to 1/2 inch and fewer pleats ... which means less surface area for filtration. Otherwise they seem ok. Quality of construction looks ok... although in1 filter (out of 6 I bought) a corner of the pleated material wasnt attached to the frame... (allows some unfiltered air past) Way cheaper, but I'm thinking that I might go back to the 3M filters for surface area and QC.