[Invalid or Expired Link Removed]
Round core, single outer wrap of nickel. Focus on fundamental. Not a lot of overtones. These are unusual strings, the E feels a bit rough because of the large wrap wire. Rough, but smooth at the same time. Smooth like nickel, not grabby like stainless.
Yes those strings are VERY unusual! Since there is only a single wrap, there is no tapering at the tuner end. The wrap just stops, then nothing but core!