Ultra wire is a non-tarnishing copper wire. It is available here in a nice variety of popular colors. Use ultra wire for ribbing, weight, flash, wire bodies and dubbing brushes. This medium size is great for fly sizes 12-16....maybe a 10, maybe an 18. Extremely popular for fly designer John Barr's Copper John's and this is the most popular size for those.
* The pricing here is not a mistake, certain colors are obviously harder to accomplish therefore a bit more expensive.