Jagwire showed me something similar At Taipei show. Basically scaled-down grey pipe lagging. The version they had featured full length slit meaning easy post setup installation. They said they're offering oem at the moment but it'll be available aftermarket soon. I'll try and get more deets.
if you can source another one, I'll come up and see you. Since you mentioned it, my rattle has gone into overdrive. v annoying today.