Series 40 All Purpose Block - Single Upright LeadLead blocks are a low profile solution for leading halyards or other rig sail controls back to cleats or jammers. Ideal for high load applications. Wear resistant sheave material, in lightweight, self lubricating polymer, is suitable for use with rope or wire.Applications:Typically used for halyards at the mast base.Materials:UV stabilised acetal sheaveGrade 316 stainless steel load housing