Used on double doors sliding on one track, meeting together in the middle and opening to give a wide access space, the doors are connected to each other via a toothed belt so that, when one door opens (or closes) the other door mirrors it automatically, so the doors open together and close together, but only one door leaf is pushed or pulled. There are simultaneous opening kits available as optional extras to both the Geze Perlan sliding door gear, and the iMpero double pocket door system.
You can now find these sliding door products on our sister site Siding Doorstuff, here.