Hope this is useful. I have a few of these and rate them highly! So much so that I have never had to replace one yet (I wear them as an underlayer), but I discovered that you can get on free upto the 20th November.
You have to subscribe to a mailing list to get the code. I found the link here:
[Only registered and activated users can see links. ]
Link to subscribe: [Only registered and activated users can see links. ]
Hope it is useful.