Keyboard Wrist Rests

Anyone here ever used a keyboard wrist rest? Did you find it effective when typing for longer periods?

I noticed two two different types on eBay.

This one which is filled with foam, though there are also similar gel filled ones;
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and this one which has rollers;
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Any opinions on either of these designs? Thanks

I had a foam-filled rest (a bit like your first example, though without the bit which goes under the keyboard) and I found it more a hindrance than a help. I do have a mousemat with a wrist rest on it which I find very useful.

The most useful aid to me is the Microsoft split keyboard. I find it very comfortable and easy to use, and now find it difficult to use the standard keyboard for any length of time. I have a split keyboard on my home and work PCs.

http://www.amazon.com/Microsoft-A11-00337-Natural-Keyboard-Elite/dp/B0000642RX (Here's) an example of it from Amazon.

Second that, I found the split keyboard much better than the standard wrist rest. The one I had was huge though. Took up a lot of space on my desk.