kp1832000,
Thank you for your question. These doors are the Fleetwood brand multi-slide doors. The bottom track is recessed into the floor and the glass door panels roll on Swiss made bearings. This allows the heavy panels to be easily pushed by even a child.
You may be interested in the other pictures of this parade home or our other sliding door ideas-
http://www.houzz.com/projects/278804/Parade-of-Homes-2012---Via-Aragon-by-Progressive-Solutions
http://www.houzz.com/ideabooks/7748282/thumbs/Sliding--Telescoping--Exterior-Pocket----Lift-and-Slide-Door-Ideas

What about a possible screen for these doors? Any suggestions?

riverplace,
Yes, screen panels are offered for this door type. The screen panels have the same frame as the glass panels, just with an ultra clear-view screen. We are working with some homeowners right now for several multi-slide door units like the above that will have no glass, just all screen panels for their outdoor kitchen. A great idea if bugs, flies, and mosquitoes are a problem! In addition to the standard screens for these doors there are several other options in this ideabook-
http://www.houzz.com/ideabooks/21091574/thumbs/Screen-Options-for-Large-Doors---Windows