They started producing the third version around 1958. Barring a few missing blades, this is pretty much the full set as it would have been sold. It also came in a Gold plated version. The key is there to set the adjuster dial, and is also used to dismantle it, I guess for maintenance.
As indicated on the main Apollo page, the plating is iffy and they are prone to getting seized up if not cleaned properly. After my experience with both the Mikron 2 and the Matador, I asked for more pictures before I bought this one.
(See below to tell for yourself that the adjustment mechanism is working)

The patent on this version was granted under patent number (number DE1030221) and was granted on 14 May 1958.

Tha same razor was sold as a Matador. It's not clear exactly what the relationship between Rasierklingen Fabrik and Matador was.

How does it shave? It shaves pretty much the same as the second version. The handle is a little shorter so I do favour it slightly over the second version.

Does the Apollo Mikron 3 that I want to buy Actually Adjust? Ok so you've seen a Mikron 3 for sale somewhere. You have also heard that the plating wasn't great and there is a very real possibility that it has seized up. How do you tell from the images? The image below will hopefully show what you should be looking out for. The top of the image shows them fully closed and the bottom shows them fully open. If you look at the area at where the arrows are pointing to, you will see that as the adjuster plate moves up and down there is a small area exposed when its open and none when its closed. This version also has a red dot that becomes visible when its fully open, although that could be worn away through use. (Clicking on the image opens it in a new tab) Its far easier to ask for more images than to reverse a transaction.