21x27x1 Trane Replacement MERV 12 Plus Carbon AC Furnace Filters 6 Pack Controllers One continuous and corrosion resistant

One continuous and corrosion resistant helix wire is placed in the duct wall for structural support

The attached reflector increases 30% efficiency

Controls heating or cooling equipment with both day/night set points

use less T-Rex and apply in the first week of vegetation only

21x27x1 Trane Replacement MERV 12 Plus Carbon AC Furnace Filters 6 Pack Controllers One continuous and corrosion resistantNordic Pure Trane Replacement 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