18x28x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack Trimmers the inner diameter at the

the inner diameter at the bottom is going to be smaller

• Dimensions: 18

On-Board Digital screen reporting

The sleek finish reduces cleaning and maintenance times and is compatible with the CenturionPro Mini trimmer machine

18x28x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack Trimmers the inner diameter at theNordic Pure Custom MERV 12 Plus Carbon air filters are made based on the actual measurements so be sure to measure your current filter to get the EXACT dimensions before ordering. As with all Nordic Pure filters, the effective life of your filter depends on the environment in which you live. We recommend changing 1 and 2 filters every 30 90 days. Our 4, 5 and 6 inch thick filters could last up to 6 months. EXACT MEASUREMENT: Furnace and air condition