Black Magic Air blocks are a top favorite of Big Boat performance racers and cruisers. These lightweight, free-running, powerful performers are used for sail controls that see lots of action: mainsheet, runner, halyard, and spinnaker systems. A center cage keeps Torlon® roller bearings separated and parallel to reduce friction. Shackle blocks lock in two directions or swivel to keep line from twisting. Torlon is a registered trademark of Solvay Advanced Polymers L.L.C.SPECIFICATIONS RESOURCES SPARE PARTSSheave Ø (mm)100 mmSheave Ø (in)3 15/16 inLength (mm)203 mmLength (in)8 inWeight (g)623 gWeight (oz)21.98 ozShackle pin Ø (mm)10 mmShackle pin Ø (in)3/8 inMaximum line Ø (mm)16 mmMaximum line Ø (in)5/8 inMaximum working load (kg)3402 kgMaximum working load (lb)7500 lbBreaking load (kg)6804 kgBreaking load (lb)15000 lb