Steel core, handmade in Denmark. Pure, warm, and even-toned across all four strings. Minimal bow noise and reliable tuning stability. 15–16.5" size, medium gauge.  Strings should generally be changed every 6–12 months, though students usually change them less frequently. Even if strings haven't broken, they gradually lose their brilliance and responsiveness — if your instrument sounds dull or takes longer to settle in tune, it's time for a fresh set.