This is it:
http://www.bowlwithbrunswick.com/accessories/detail/slide-stone/

This seems to be a new-ish product to add slide to your sole. A teammate showed it to me last night and said it's legal at Nationals (one of the fussiest places) and everywhere.

My question is how does it work.  It seems like a just a hard piece of marble-like material. It must leave no residue for it to be legal all the time.

I'm worried if it works by flattening out any standing fibers on the sole. If it does that, it may flatten them out permanently. I wonder if a nylon brush could restore the sole for the next time when the approaches aren't so slippery.

I don't really want to experiment and destroy $15-20 sole replacements.

It looks like soap stone glued to the bottom of a wood handle.  People have been using soap stone for years on the bottom of shoes.  You can buy it at any hardware store.

It looks like soap stone glued to the bottom of a wood handle.  People have been using soap stone for years on the bottom of shoes.  You can buy it at any hardware store.

Around here, Home Depot and Lowe's have put virtually every hardware business out of business, except for a few scattered Ace Hardware stores, which I used to love to browse.

But I understand what you're saying. Thank you. I'll see if I can find a piece of soapstone somewhere locally.

Do you think this means that pieces or particles of the soapstone somehow adhere to the sole or does the stone just press the nap flatter?

Soapstone is high in talc content, thus the slide, except it doesn't come off on the approach to bother another bowler.  Good stuff to have in a pinch.

You can brush your shoe and get it off again should you want to. 

I haven't seen too many people rub the stone on their shoes.  Instead, they scrape off some of the material into a powder then apply that to the shoe.  But I haven't seen anyone with one in several years.

Soapstone works really well. I've had it in my bag for a few years now. I like it cause it doesn't mess with the other guys approach and gives me slide when I need it

I found mine in the welding section at a home depot

I don't know if this is brunswicks, but I found the patent for it.

http://www.google.com/patents/US20050177963

"The present invention provides an applicator comprising a body of solid  soapstone or appropriate lubricant in a holder or handle for applying  the soapstone to a bowling shoe sole."

I found mine in the welding section at a home depot

That's exactly where I found it today. This one is long, 1/2" x 3/16" x 5", but I got 4 of them for $3.50. Also have the Brunswick one on order from Cliff Barnes Ebay Pro shop.