Hi Roz, Thanks for the question. Although it has been awhile, I remember this was an All Weather multi slide/ stacking slider. The overall width is 16', allowing for ~32" sliding units. The two outer panels are fixed, and the center 4 operate.

https://www.houzz.com/photos/mid-century-remodel-midcentury-exterior-san-francisco-phvw-vp~82304442