Introducing the HD31 project:

The project offers a solution to the issue of increasing the number of passengers in the cabin of a single-aisle airliner by increasing the space between seats by 15%, giving each passenger four more inches of available leg room. By alternating the direction of seats and modifying the layout, a high density economy cabin is actually a reality. 

See the video explaining the concept.

HD 31 stands for High Density at 31-inch spacing and it was presented at the Aircraft Interiors Expo in April 2014. Earlier that year, Zodiac Seats had presented the now-available L3 concept, the most lightweight seat on the market.

In 2015, Zodiac Seats introduced another exploratory concept: the LifeStyle cabin presents a vision of a completely different airline cabin architecture by redefining the space into multiple living and communal areas, as well as using a section of the cargo area as a mini suite.