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Ronstan "Orbit" Ball Bearing Block - 55mm - Single / Becket / Swivel Head

Ronstan "Orbit" Ball Bearing Block - 55mm - Single / Becket / Swivel Head

SKU: 504663

$45.853 / EA

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Orbit™ Ball Bearing Block - 55mm

Series 55 BB

Kilogram for kilogram of working load, Ball Bearing Orbit Blocks™ are the world's lightest. The unique orbital design allows the bearing to be only in the active areas of the floating sheave. Weight and bulk are further reduced in the different block configurations. The ball bearing single with becket blocks have a through-sheave becket arrangement. The result is the lowest weight possible.

Block RF55110 features a stainless steel, swivel shackle head for unlimited block rotation and ultimate durability. It also has an ultra-low-profile integrated becket.


  • Ultra lightweight
  • Low friction 2-stage Orbital ball bearing system
  • Highest working load in its class
  • Low profile and compact
  • High-performance cleating
  • Stainless steel swivel shackle head


  • Ball Bearings - High compression strength, carbon black Acetal
  • Stage 2 Bearing - Carbon fibre reinforced, PTFE-impregnated Nylon
  • Frame/Cheeks - Toughened, glass-fibre-reinforced Nylon
  • Sheave - Carbon fibre reinforced, PTFE impregnated Nylon
  • Rope Link - UV stabilized, multi-strand impregmented SK75 Dyneema®


  • Mainsheet systems on dinghies, sport boats & small keelboats to 30 ft. (9m)
  • Spinnaker sheets on dinghies, sport boats & small keelboats to 30 ft. (9m)
  • Halyard, vang & backstay applications on boats to 26 ft. (8m)
  • Control line applications on larger yachts


  • Sheave Diameter - 2-5/32" (55mm)
  • Max Rope Diameter - 3/8" (10mm)

Mfg No. RF55110

Description Single / becket / swivel head

Max Working Load 1,100 LbsA (500kg)

Breaking Load 2,200 Lbs (1,000kg)

A. Total block load. Load on becket not to exceed 50% of block load, i.e., MWL 550 Lbs (250kg), BL 1,100 Lbs (500kg). Suitable for 2:1 system at rated block load.

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