[Ron Ramirez]

The pole piece is indeed solid.

But the problem here is that the screw goes through the spider, and the spider is solid - one wrong move and bam, major damage to spider.

Even if the spider were open, what I call the "45 rpm adapter" type because its appearance is very similar to a 45 rpm adapter which is inserted into the large hole of a 45 rpm record, one wrong move with the screwdriver and hammer and bam, broken spider.