It is the dry lube that is mixed in the hopper with seeds that keeps all of the airways slick. Very good stuff. I use the old IH graphite that came in a quart or so shaker bottle. The stuff is so fine that it can be placed in a tiny squeeze bottle with a spout on it and can be puffed into places.
Mine is straight graphite... not super cheap, but goes forever. I have not used anything other than the IH product and is states 100% graphite, ultra fine. Will look this weekend, might even list the particle size.
I would have in the past, the Indy 1500 always had a couple of good TC vendors but not so much anymore. I will also contact Ed Kirkpatrick about a spare.