The bottom most layer
is a piece of cotton
canvas.
In this picture it is
velcroed in place in
the cockpit.
You may be able to make out
the stitches where I sewed
on the velcro.
I used 2 stripes of 2" wide
velcro and a strip at the
back, and few tabs on a
a flap in front of the seat.
From what I can tell this
method works really well.
There's no way these seats
are going to move unintentionally.
But if you want to remove them
the pull right out.