My old mailbox is sitting on a 2 7/8" pipe embedded in concrete sidewalk. Will this fit over the pipe?

Hello, the opening of Architectural Mailboxes Concrete Pad with Base Bracket Black Steel Mailbox Post, Model# 5526B measures 3.8 in x 3.8 in. so it should fit over your 2 7/8" diameter pipe. The post measures 38 inches high, so ensure that the pipe's height is less than 38 inches. We still recommend bolting the post to the surface. Thanks for reaching out!