This sale is for a very rare and near mint condition RB67 Pro 645 viewfinder mask. It is suitable for use with the RB67 120 645 backs (all models) on any RB67 camera – Pro, ProS or ProDD.
This is really hard to find mask has only really minimal signs of use, and is completely flat – not bent or kinked like most.
Try finding another one – really really hard to find.