Re: swivel seat adaptor (rtt108)
I'm not sure, I didn't measure. It looks to be somewhere around 1.5". It is noticeable.
Flipping the studs over is done from the inside. It's very easy. Look where the seat base goes into the floor, remove the studs. Move the seat base out of the way, flip the studs over, reinstall. If you are planning on installing the swivel, that would be a good time to flip the studs.
The swivel seat is highly useful, but remember it will only work with the passenger side rear facing jumpseat removed.
Az