Hi Chris,
I've got the stuff beside me now. The base material is a fairly stiff gauze, quite an open mesh. The "fur" is long strands of fine nylon (or something similar) that is attached to the surface of the gauze. I'm not sure whether it's stitched to the backing or glued. Fibre length varies between about 1" and 4", and quite closely packed.

If I put a double layer over my ears, I don't hear any reduction in the volume of the background hum of my computer fan, so I'd say it's pretty transparent acoustically. However, all those very fine furry fibres absorb some of the energy from the wind.

I'm not sure that the stuff I have is necessarily the best. I've noticed that Rycote uses shorter fibres, and all the same length. You will actually see them waving in the breeze... That's probably the sort of characteristics you should look for.

Let us know how you get on.

(My keboard's covered in little hairs now...)

Thank you very much for taking the time!

I think it's time to consider cutting up the wife's fur coat!

Unless it was bought from Tar-zhay (Target), maybe you should consider going to a fabric store for cheaper fur. :]