What size signposts does your sign base support? Can I use round, square or U-Channel signposts?

We have 3 signpost hole sizes. They can be ordered with a square hole to accommodate a 1-¾” square perforated or smooth, square post with drilled holes. The square hole base will accommodate a U-channel post as well. We can also custom-fabricate square tubes to any configuration and powder coat any color. We also have sign bases with a round post holes to accommodate a 2-⅜” round Schedule 40 plastic post or aluminum post and a 1-⅔” round post. The round plastic 2-⅜” post is our most-popular signpost base.