Is there a rocket mass heater that is commercially available?

Hi, interested in a model I saw a picture of and wondering if anyone manufactures them for purchase?
I searched again (here and Google) and did not find the picture again.
Thanks in advance
Sage

Something like this one, is what i mean. https://permies.com/t/18064/wood-burning-stoves/Rocket-Mass-Heater-modern-works

Zaug stoves are apparently for sale: http://www.zaugstoves.com/wordpress/

Also, Dragon Heaters has a precast core kit which can be encased in any shape of masonry or cob surround to make a reliably engineered and efficient unit: http://www.dragonheaters.com/