Quote Originally Posted by StoneNYC View Post
That seems so strange why would they be supporting two of the same basic 67 systems? What is the pro ass model then have the same kind of advanced features where you could advance the film with the same cocking lever as the mirror?

(Edit: okay I was dictating with Siri, and that's what she said, ironically, but actually I meant"Pro-S model").
RZ67 Pro was introduced in 1982.

The RB67 Pro-SD was introduced 8 years later in 1990 - it replaced the RB67 Pro-S which had been current for 17 years.

The RZ series may very well have been intended to eventually replace the RB series, but not immediately.

With the RZ series you lost functionality in some areas, while gaining in others. It certainly didn't make the RB series equipment second class.