100 mm Aluminum Black Magic Runner Block

The workhorse of the Harken line, the entire range of Black Magic® AirBlocks® has been redesigned with a sleek new look.
Their unique, performance-packed engineering remains exactly the same.
Used on offshore boats, these strong, lightweight blocks feature aluminum cheeks, and free-rolling, high-load Torlon® roller bearings for a high strength-to weight ratio.
Use them for sail controls that see lots of action — mainsheet, runner, halyard and spinnaker systems.

Easy Maintenance —
AirBlocks are easy to clean and service.
They have few parts and no loose balls or rollers to misplace.
Unlike blocks that are riveted, fasteners allow quick disassembly with a single hex wrench.

Low Friction Caged Bearings —
Roller bearings are housed in a unique center cage that keeps them separated and parallel for lower friction.
Dirt and sand falls out between the rollers.
Captive Delrin® ball bearings carry any sideloads.

Strong, lightweight sideplates and sheaves —
6061-T6 aluminum sideplates are sculpted to remove excess weight.
Thin-profile, deep groove aluminum sheaves have radiused edges to protect high-tech lines.

Long-lasting protective finish —
Sheaves and sideplates are deep-saturation Hard Lube-anodized for strength and durability.
UV stabilized, and PTFE-impregnated for maximum protection and a smooth, slippery surface.

• 30% lighter, 60% higher working load than equivalent sized ball bearing blocks
• High- and low-load versions
• Breaking load is 2 times safe working load
• Sheave diameter: 3.94" (100 mm)
• Dissimilar metals isolated to prevent corrosion - plastic isolators under all fastener heads and headposts
• Three-way head - set screw locks shackle in front or side positions, or lets block swivel to keep line from twisting