Could you be talking about hardware cloth?
Here's a pic of 1/4" hardware cloth that we like to use on our runs.
We get ours from either Lowes or Tractor Supply:
http://www.tractorsupply.com/webapp/wcs/stores/servlet/DisplayCategory_10551_10001_140216_14375__14345%7C14359%7C14375
It may be...