I haven't used the Hearthkit, although I've ordered it from many suppliers - all of whom are waiting for stock.
I finally phoned the manufacturer and was told that the 19" size was discontinued long ago. Apparently, Hearthkit does not believe in letting its distributors know that the 19" kit is a thing of the past, so orders just keep piling up, and folks are getting angry at their retailers, when in truth, Hearthkit has failed to communicate.
If you're lucky enough to be able to use the larger size stone, its still available. This may be a great product, but the company could certainly use some common sense. I wonder how many orders are laying around at Amazon for the 19" unit, waiting to be fulfilled. Pretty stupid of HearthKit, huh?