It's not written anywhere, but the strings are suitable for a long scale of 864 mm (Thunderbird) - nice. Unfortunately, they are dirty and leave a steel residue after taking them out of the packaging (the same deposit was on the fabric wrapping. The round brass hooks are cast, not cut like in the case of all manufacturers (this indicates savings), but this does not ultimately mean anything bad. Comparisons with other strings of this type I don't have flatwound, so it's hard to judge their sound.