All the California hoopskirts have smooth bases, but there are differences between the mold types.

The blue taper top molds have a flat slanted base. The blue aqua taper tops have either a flat slanted base like the blues or one rounded in cross section like all the square dome mold hoopskirts. This particular one has a rounded smooth base. The aqua square dome mold has a rounded smooth base like all in this mold type.