The bottom overlaps the
back at 45 degrees, locking
the back in place.
I used a little bit
of the green foam on
the seat back as a first
layer to give just a little
lumbar support.
Most automobile seats have
way to much for my back and
and wind up giving me a
colosaul back ake on long
road trips.
Yet I can set in a plane ol'
chair all day long with no
pain. The seats turned out
very comfortable.