This one is incredibly rare and is only the second one I have ever seen for sale in the past 10 years.
PENTAX 645 AUTO BELLOWS | eBay
I bought a new one and still have it. This one and it appears "all there" except for the manual and the "wired" camera connection, It does not use a dual cable release and does not come with magnification scales like other Pentax bellows units. The camera is triggered by single cable release and an "wired" cable back to the 645 body. If you are using a 645D or Z not an issue. You can still wire these but it takes some work.
Murray
PS: I can supply a hi-res PDF Manual if anyone is interested.