Instruct: Classify a given Amazon review as either positive or negative.
Query: Gets the job done

I've been using these for 5 years (the Ultra 1250 MPR) and haven't had an issue. I change them once every 4 months (instead of every 3 months) based on a visual inspection. I don't know if it restricts air flow or not, but my furnace & A/C (same blower for both) have worked fine for 5 years so I'm not going to complain.