Mystery piece

[Ulophot]

This came in a lot darkroom items I recently purchased. I thought, at first, it might be part of the Patterson System 4 tank system, but it doesn't appear to be and the message, "Warning: Always keep CD wet while resurfacing" is anomalous. CD resurfacing?

[Jon Shiu]

Probably for CD, DVD etc polishing machine that takes out the scratches.

[Jac@stafford.net]

Note how the center is built to lock/trap a typical cd onto the surface. What you see is the drive gear.

[Ulophot]

Thanks to both. Just couldn't understand why such a thing would be in with darkroom materials. Creeping digitization strikes again!