Harken 2643 40mm Carbo Air Double Block with Becket Fixed Shackle

The Harken 2643 40mm Carbo Air® Double Block with Becket is a high-performance sailing block engineered for low friction, exceptional strength, and lightweight construction. Featuring a fixed shackle mount and an integrated becket, this double-sheave block enables efficient 2:1 or 3:1 purchase systems for mainsheet, jib sheet, and spinnaker sheet applications on sportboats, dinghies, and small keelboats.

Part of Harken's acclaimed Carbo Air® line, the 2643 is consistently 30% lighter and delivers 60% higher working loads than equivalent Classic blocks — making it an ideal upgrade for performance-minded sailors who demand more from their rigging without adding unnecessary weight.

Key Features:

• Open Air Block design eliminates excess material and reduces overall weight
• UV-stabilized ball bearings, sheave, and side plates with carbon black treatment for maximum protection against sun, salt, and weathering
• Free-running ball bearings roll on curved races for smooth, efficient load distribution
• Fixed shackle with patented switch locks in front or side positions, or allows the block to swivel to prevent line twist
• Fiber-reinforced composite construction provides a superior strength-to-weight ratio
• Becket included for attaching the standing end of a purchase system
• Compact, small-footprint design suited for high-performance dinghy and sportboat rigging
• Compatible with small-diameter lines favored by racers

The Harken 2643 is an excellent choice for jib and mainsheet systems on high-performance dinghies and control lines on small keelboats. Its proven Carbo Air® construction has earned both the Dame Award and Sail Magazine's Freeman-Pittman Award for innovation in sailing hardware.