HD31 project: an exploratory concept developed by Zodiac Seats
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. HD 31 stands for High Density at 31-inch spacing. The now-patented HD31 concept 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.
See the video explaining the concept: https://youtu.be/RCGVpTzF2xI