100% double nap cotton flannel patches, color white.
lots of places sell them. Midway Oxi-Oak, Pro Shot, Dewy, etc.
Material and size (1.75sq) is more important than "Brand" name.
I used to goto the sewing supply shop for patches. Cut them to size using a paper cuter. Now I just buy in bulk.
http://www.ar15.com/archive/topic.html?b=3&f=7&t=265811
used with a 30 cal brass jag from dewey and midway brand, loop requires 2 patches never that tight. Have wrapped a patch around a worn brush and used that in a pinch.