What's a Sinar DB mount ?

I see lenses I would like to bid on on e-bay but they
are mounted in a Sinar DB mount. The close up photos
of this mount discourages me. I'm afraid it will
be  a  problem re-mounting the lens elsewhere.

What's this mount and is it feasable (and easy)
to remove a lens from this kind of mount and
put it on another plain board.

Is the shutter and iris somehow married to this board ?
What's the deal with this db nount. Are all Sinar boards
like this ?