Linked blinds are when you have two or more blinds side by side in the same window or door frame sharing a single middle, or intermediate bracket.

Linked blinds are particularly useful when you have a large stacker and bi-fold doors and ranch sliders that are too wide or oversize for one blind – by splitting it into two separate blinds it allows you to have one chain control for each blind or one chain control for two blinds. 

Here in New Zealand where we often have large door sets for indoor outdoor flow – linking your blinds together will reduce the gaps between the blinds and allow you to keep the chains to the sides of the frames.