18x30x1 Pure Green Eco-Friendly AC Furnace Air Filters 6 Pack – Grow It Depot
18x30x1 Air Filter | MERV 8 | Filter King
18x30x1 Air Filters MERV 11 - Only $9.25 per filter!
Filtrete 18-in W x 30-in L x 1-in MERV 12 1500 MPR Allergen, Bacteria and Virus Electrostatic Pleated Air Filter in the Air Filters department at Lowes.com
18x30x1 Filtrete Clean Living Comparable Air Filter MERV 8 - 6PK