Lomanco Alum Gable Vent 14"x24" White 12" x 12": overall size 15"x15"; 56 sq. in. net free area, 5-1/2 lbs/ctn 12" x 18": overall size 15"x21"; 90 sq. in. net free area, 7-1/2 lbs/ctn 14" x 18": overall size 17"x21"; 106 sq. in. net free area, 8-1/4 lbs/ctn 14" x 24": overall size 17"x27"; 146 sq. in. net free area, 10-1/2 lbs/ctn 18" x 24": overall size 21"x27"; 190 sq. in. net free area, 12-1/2 lbs/ctn