I have three used sets of what I think are: One set of roto 66's 2 sets of daddario nickel rounds What I believe to be roto's are definitely steels and have red silks at the tuner ends. The other 2 are silkless and have multicolor ball ends. They feel like nickel to me. They're all longscale. They all seem to be medium gauge. $20 shipped conus for the trio.