This set contains all you need for a complete passage function installation for double doors (latch secures active door, but can be opened from either side by turning knob).  knobs on inactive leaf are attached with dummy mounts.  (furnish a flush bolt of your choice to fix inactive leaf in closed position.  For entry functions (exterior doors) also order a dead bolt or furnish your own. For privacy functions (bedroom, bath, etc.) add a privacy latch, or single cylinder dead bolt.