Series 40 Ball Bearing Block - Single Upright LeadLead blocks are a low profile solution for leading halyards or other rig sail controls back to cleats or jammers. Precision molded Acetal sheaves running on Acetal or Torlon; ball bearings provide high performance & low friction. The 2-stage ball bearing system provides consistent performance over the full load range.Applications:Typically used for halyards at the mast base.Materials:Acetal ball bearingsUV stabilized Acetal sheaveGrade 316 stainless steel load housing