Microfiber Cleaning Cloth/Gray Card

While looking for gray cards I came across this item. Its a micro fiber cleaning cloth and gray card combination.

What do you guys think?

http://www.cleanstar.n​et/

They are selling for $7.50 on ebay.

I presume that its tonality is 18% gray, but it might not be neutral for White Balance.

Yes it's 18% the only thing I'm worried about is light coming through the other side.

photagraph wrote in post #10184340
Yes it's 18% the only thing I'm worried about is light coming through the other side.

It seems that you did not read and understand Wilt's post. The "gray" may have a tinge of one color or another in it, rather than being equal parts blue, red, and green - "neutral".

If it is not truly neutral, it is not a good target for a color reference. It would be fine for using for an incident exposure measurement with a reflected light meter but not as a color (white balance) reference.