It's basically a glove that's got normal material one side for washing & the other side has a clay like texture, wash the car & then go over it again with the clay side of the mitt using soapy water as a lubricant-gets all the surface contaminants off just like a clay bar does.
Got ours from halfords so they should have it on their website
Regards
I recently bought a clay cloth, I haven't used it yet. I have never clayed a car before, but read a lot of positive things about the clay mitt/cloth being a very good easier to use alternative.