Harken 2.25 in (57 mm) Blocks The 2.25 in (57 mm) is the original Harken® block. They are compact and lightweight, with fast trim and release under high or low loads. Perfect for dinghies, scows, beachcats and iceboats, as well as small offshore racers and cruisers. Free-rolling Delrin® ball bearings, sheave and sideplates UV-stabilized with carbon-black additive for maximum protection. Use for: Main and jib sheets Spinnaker halyards Control lines