K&N 57i performance injection air filter kit: Ford Focus Mk1 1.4/1.6 -05
Air Cleaner Box with Window | Ford Focus ST Forum
Black Green Air Intake Kit & Filter For 2012-2018 Ford Focus 2.0L 4Cyl | eBay
2012 Ford Focus Oil And Filter Change - iFixit Repair Guide
Fuel Filter Kit, 2016+ Focus RS
Focus Air Filters - Best Air Filter for Ford Focus
Ford decided to be special and make an air filter unit with a replacement part that costs $200. Made my own for $30 of parts and some tape. : r/techsupportmacgyver
Ford Focus Series (07-18) DNA Air Filter R-FD16H21-01 - DNA Increased Air Flow +49.07%, DNA Filtering Efficiency 98-99% - FRD-FCS - DNA Filters - Product Details
COBB Tuning - Ford High Flow Filter Focus ST 2013-2018, Focus RS 2016-2018
Replace Ford Focus Air Filter MK2 (2005-2008) - James Simpson
For Ford Focus Escape 2012-2018 Hood Air Box Cleaner Intake Filter Cover Trim | eBay