I just built an outdoor fireplace and used 16" x 16" flute. The flute protrudes a little over an inch from the brick. This cap is advertised as fitting 16" - 19". The 16" square dimension is the size of the mesh, so my flute essentially fits inside the mesh square. I want to point this out to help others understand what the overall size of the base is. It works and looks good, so no issues here.