This sale is for a mint, probably unused Mamiya RZ67 electrical contacts cover, suitable for use with the RB67 PD Prism and RB67 PD Chimney Finder when used on a RZ67 Pro or Pro II body.
This cover actuates the metering switch located on your RB67 PD finder. Without it, the metering will not work. Try finding another one – these are almost impossible to find and essential if you want to use a RB67 metered finder on a RZ67 camera. The original instructions (which are also in English) are included.