Caliza HVAC Pack — 12x18x1 MERV 13 (6-pack)

12x18x1 MERV 13 pleated furnace filter, 6-pack. Nominal size 12×18×1; actual size is typically about 11.75×17.75×0.75 inches — measure your old filter before ordering. Aerostar filters manufactured in Orlando, FL via Factory Direct Filters. Replace about every 60–90 days under normal use.

This shows the type of filter. It may not be the exact size. Use the dimensions in the title.