Zaandam or Zaanse clock rider pendulum 10 1/4″-11″ or 26- 28 cm long. With regular hook up to the suspension spring. Suitable for Hermle or FHS clock works marked 31 or 32 cm WITHOUT LEADER. Suitable for Schatz hook-up to square in leader. Extra long threads 6 cm so it is usable as 26 cm pendulum as well.