Any question answered...

Black rubber
They do other sizes and thicknesses, including 'ribbed for her pleasure'. Will make your study/office stink like Rob of Amsterdam for a few days while the excess solvent boils off, which may or may not be a selling point.

Kinky. Heads-up about the potential stink is very useful considering said desk is in bedroom. Otherwise looks the business, maybe I could air it somewhere.

Much appreciated, as always.