11 X 16 X 1 Square Front Flange Attic Exhaust Vent

https://onyxxteriors.com/info/explore/11-X-16-X-1-Square-Front-Flange-Attic-Louver-Exhaust-Vent.php

At 11 1/4 inch x 16 1/2 inch, this custom vent was made to fit a gable wall opening of 11 3/4 x 17.

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Square attic louver exhaust vents

When dealing with custom gable vent measures, there is no template to go by.

Custom means manufacturing any size vent needed.

Without restrictions.