The lightweight 57mm Carbo Blocks have a high load capacity and broad working range. Use for main and jib sheets on centerboard and keelboats like Lightnings, Dragons, Solings, J/24's and catamaran mainsheets. • 60% stronger and 30% lighter • Long glass fiber injection molded • Attachment applications and uses are limitless • Use for main/jib sheets, spinnaker halyards and control lines