Ozman - my guess is you meant this page...
http://www.emagictricks.co.uk/product_i ... ts_id=3443
I don't actually have this - but I do have a fair few brass effects and could probably hazard a good guess at how it is achieved. I would say it does pretty much what it says - you place a ring on the bolt, you secure it with two nuts - probably requiring quite a few turns (and consequently time to put it on) and yet within seconds - probably under a silk - or in your pocket you can remove it.
If it works as I think - then it wouldn't surprise me if it can also be put on in seconds too - in other words you could disappear the ring - and then take it out your pocket already on the bolt, secured by two nuts.
In saying all this - you have to remember I am guessing, but the price looks pretty good for a nice looking brass effect.