Here are the exterior dimensions of the post anchors. The 4x4 post anchor has an outer dimension of 5x5. The 6x6 post anchor has an outer dimension is 7.5x7.5. Both will have the anchor sticking out beyond the wood post and a post sleeve typically fits directly over just a nominal 4x4 or 6x6 post. The inner dimension of the post sleeve would need to fit over the outer dimension of the post anchor base.