The measurements should state clearly at what points on the plant saucer were they taken from... inside circle or outside circle lip edge. I had a 12” base pot and ordered the 15”.  After receiving it I discovered the 15” is the inside circle and the total size from outside edge to edge it measures 19”. It looks too large for the pot.  It will cost me another $10+ to return for an exchange. They were pricey, so I am frustrated to pay more since it was not clearly stated.
The quality is sturdy if you can order the correct size.