I was just given (people are concerned about the environment - I guess if they want to keep things out of a landfill they just get ahold me of) a Mamiya Film pack adapter for Mamiya RB.

Fits Graflok back too. But when one sees the term 'film pack adapter' it usually conjures up images of non-existent film formats.

The film pack was described as '520', 2-1/4x3-14 OR 2.5x3.5.

Can someone please describe what this is or was and whether it has any utility?

Like maybe a one shot film holder with a spacer, unless sheet film is larger than film pack sheets? Since the instructions say OR 2.5x3.5 it should have room for normals sheets?

Both my wee press cams are spring back - may do me no good there.

Thanks

Murray