The reissue SL has been Niobium the whole time, I think. It was when I bought some back in 2010. Didn't they discontinue SL for a long time? I don't find Niobium that hard to file, but a beginner would be wise to start out with thicker tubes, 9/6/9, at least. I rough cut my miters with a cutoff wheel in a dremel and then file.