Nordic Pure 18x18x1 MERV 13 Pleated AC Furnace Air Filters Plus Carbon, Box of 12 Actual Size of Carbon Air Filter: 17 1/2 x 17 1/2 x 3/4 Activated charcoal flat panel added to increase odor control Removes tobacco and fireplace smoke, along with all contaminants removed by a MERV 12 filter Ideal for customers looking for superior filtration but needing an odor control element Made in the USA