The Garnish for Fan-Tastic Vents Roof Vent # FVK2040-80 is square, but it does have a slight round at the corners. The Garnish for Fan-Tastic Vents Roof Vent # FVK2040-80 is the most square ceiling garnish that we have, it has the least amount of round at the corners and it can be trimmed down to the 2 or 3 inches you are needing. view full answer...