They look and are described like another product DAG offers. His screw into the M eyepiece, are made of plastic and shield one's glasses against damage from the apiece.
I think the Rubber Eyecups are better for that purpose. These use real rubber which is soft and can be pressed against w/o concern.
I got 2 for my M6ttls.
Note also, I discovered these will fit the Leica magnifier which has the same threads as the eyepiece.. That's comforting to know with that sucker stuck out behind the body and your eye against it. I was always fearful of being bumped while focusing. That could go into your eye w/o protection.