18x30x1 MERV 2 Non Pleated Air Filter Replacement Filters (Actual Size 17.75 x 29.75) - 3 Pack 12" Round Duct Pipe actual front end outer dimensions

actual front end outer dimensions are approximately 20 5/8" width X 14 5/8" height

and ventilators

Designed with a ring base for flexible installation

+ Product Details Size - 8"w X 6"h X 2"d (for duct opening measurement only)

18x30x1 MERV 2 Non Pleated Air Filter Replacement Filters (Actual Size 17.75 x 29.75) - 3 Pack 12" Round Duct Pipe actual front end outer dimensions+ Product Details 18" x 30" x 1" replacement air filters for your furnace, air conditioner, heat pump, or HVAC system (actual size: 17. 75" x 29. 75") A unique combination of cotton & synthetic fibers gives you the most filtration and the least air resistance equals great air & easy airflow for your system. The non pleated design provides low airflow resistance while still effectively capturing dirt and particles such as standing dust, spray paint