Identifying Mamiya rb67 focusing screen model/purpose

[Achrilidies]

Hey Everyone!

I recently got myself a Mamiya RB67 Pro SD(90mm f/3.8 C lens, and a CDS prism finder) from a local camera shop. Ive been pouring over the functions of the camera for the last few days learning all of its insanely engineered wonderfulness. The one thing I cant seem to be able to pin down exactly is the model/purpose of the focusing screen it came with.

I understand the far left and right dotted lines frame the shot while the camera is set up for portrait (and the red bars that appear while in landscape). The rest...not sure. Any information would be greatly appreciated. Thanks much!

 

[John Koehrer]

Might be 645.
Never seen one up close & personal though.

 

[juan]

There was a 645 back for the RB67.
juan

 

[MattKing]

Looks like an extra set of lines added for the 645 back.

Great - I'd much prefer that to the removable 645 mask I have.

 

[j-dogg]

645 screen

 

[Achrilidies]

Thanks guys! That seems to make a lot of sense. No real use for it, but nice to know. cheers!