We just added them to our site, see http://www.brassaccessories.co.uk/www.brassaccessories.co.uk/info.php?p=24
There's also a video to watch.
OUR PRICE £39.95 +p&p.
Hope this info helps.

I am wary of embouchure exercisers. Yes, like freeweights in a gym, they can be useful to build strength and mass, but aren't we more concerned about flexibility and endurance? Misused, they can cause more harm by exercising the embouchure the wrong way and sacrifice flexibility.

The aspect that concerns me most is that what brass players need most, firm corners of the embouchure in order to help everything else work properly, does not seem to be what these appliances exercise best. They seem to exercise the middle of the embouchure, which can lead to a false sense of security without working properly on the corners of the embouchure.

In the three weeks or so I've had them on our site I've sold a couple, I haven't really tried one out over a period of time yet although a seasoned teacher has told me that many years ago he had his pupils put a small button on a thread to produce a similar exercise.

I bought one of these a couple of months ago actually, from the US.  I cant really comment on its efficacy though.  I only used it intermittently and as an inexperienced player can't place it's affect, if any.  In any case, it would be so easy to replicate the object at home.  I would think a tea spoon with bends in the right places would do the trick.