This sale is for a mint condition Mamiya RZ67 Pro Electrical Contact Cover, suitable for use on the Mamiya RZ67 Pro, Pro II and Pro IID cameras. Original instruction sheet included (and of course it is also in the Downloads section).
This is a unusual accessory was supplied new in the box with all RZ67 Pro cameras – but was almost always lost. It allows you to use metered RB67 viewfinders (all types) on your RZ67 and still be able to use the metering. Without this adapter you lose all the metering. Not required with RZ67 viewfinders of course.