The Eclipse Red ring is amongst the most well known Adjustable razors. They were manufactured at a time when blades were thicker and had more spring in them. Using the current DE Blades I would not consider them to be adjustable.

My understanding is that there are 4 different generations: (Dates are approximate)
Gen 1: 1933 - Silver Plated 3 Piece with embossed logo on the top cap and no painted Red Ring.
Gen 2: 1934 to 1936 - Silver plated handle, Chrome Head 3 Piece with Embossed logo and no painted Red Ring.
Gen 3: 1936 to about 1939 - Chrome Plated Two Piece. The twist knob was pinned into the handle, there was an embossed logo on the top cap and the ring had Red Paint.
Gen 4: 1939 to 1940 - Chrome Plated Two Piece (pinned twist knob) and no Embossed Logo. The ring was painted Red

They are a Open Comb / Solid Bar Hybrid.
All have the magnet in the bottom of the twist knob, which is probably their most famous features.
Another is the words Eclipse and Red Ring engraved into the handle.

I own a Gen 3 and a Gen 4.