Ronstan Series 30 Ball Bearing Block - Single - Loop Top [RF30101]Series 30 Ball Bearing Block Single Loop Top Features: Low friction 2 stage ball bearing system provides consistent performance over the full working load range High static and dynamic load capacity Light weight Versatile head fittings Sheaves running on Acetal or Torlon ball bearings provide high performance & low friction Can be fitted with a shackle in either of two planes to allow correct alignment of the block Applications: Primary lead blocks on