This is an option too.Less expensive, but rather inconvenient.
First you put on the ground glass with a mask....
then you remove it, put on the adapter plate take one shot....
then remove it to rotate it 180 and do a second shot....
You then have to remove and reverse the adapter plate and repeat
the last two steps. When you are done in order to stitch the images you also have to rotate them.
Kapture Group makes a much better one nothing has to be removed to take shots.
Much nicer solution, just a bit larger.
Oh crap.... now I'v pissed off B Cooter again for posting an animated gif.