[MrFixr55]

Same here. I have never seen these coverings and don't know how effective they are when the front of the voice coil is not covered by anything other than the grille cloth.

It is interesting, as many radio speakers, from the 30s up to about 1950, including those with the more modern phenolic corrugated "spiders" do not have dust caps on the cone, covering the voice coil, let alone this cloth covering on the frame. Sets with this cloth covering usually do not have that felt dust cap over the voice coil. It was understandable that the original speakers where the "spider" almost looked like a spider, but more like the 45 RPM adaptor. These were not covered because of the screw that held the spider to the magnet pole piece.