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Ronstan Series 55 mm Ball Bearing Orbit Block

  • Type: Quad Block with Becket & Swivel Head
  • Safe Working Load: 1650 lbs.
  • Maximum Line Size: 3/8"
  • Item #: 
    Model #: 


    Shipping Weight: 
    0.70 Lbs.
    List Price: 
    Status:  null In Stock

    Quantity : 


    Ronstan Ball Bearing Orbit Blocks™ boast the highest strength-to-weight ratio available. This is achieved through all-composite reinforced polymer materials and a Dyneema® rope link head. Their precision design allows the optimum number of ball bearings in loaded areas and eliminates them in inactive areas. Ineffective mass is reduced even further through fiber-reinforced composites in the block head, cleat arms and beckets.


    • Ultra Lightweight
    • Low friction 2-stage Orbital ball bearing system
    • Highest working load in its class
    • Low profile and compact
    • High performance cleating
    • Swivel shackle head for unlimited block rotation.
    • Stainless steel shackle head for ultimate durability and compatibility with harsh fixing points.
    • Ultra low profile integrated beckets.


    • Mainsheet systems on dinghies, sportsboats and small keelboats to 9m (30ft)
    • Spinnaker sheets on dinghies, sportsboats and small keel boats to 9m (30ft)
    • Halyard, Vang and Backstay application on boats to 8m (26ft)
    • Control line applications on larger yachts
    • Mainsheet systems and spinnaker sheets on dinghies, catamarans, sportsboats and small keel boats to 9m (30ft)
    • RF55410 when paired with a RF56330B and a RF35101 lashed to the becket produces a powerful 8:1 mainsheet system for use on catamarans to 5.5m (18ft). This can be increased to 9:1 by replacing the RF35101 with a RF35202
    • Halyard, vang and backstay applications on boats to 8m (26ft)
    • Control line applications on larger yachts


    • Sheave: 2-5/32"
    • Max. Line Size: 3/8"
    • Max. Working Load: 1650 lbs.*
    • Breaking Load: 3300 lbs.*
    • Weight: 11.2 oz

    *Total block load. Load on becket not to exceed 33% of block load. ie. MWL 250kg (550lb), BL 500kg (1100lb)


    • Ball bearings - High compression strength carbon black Acetal
    • Stage 2 bearing - Carbon fiber reinforced, PTFE impregnated Nylon
    • Frame/Cheeks - Toughened, glass fiber reinforced Nylon
    • Rope Link: UV stabilized, multi-strand SK75 Dyneema®
    • Head fitting: grade 316 stainless steel
    • Ball Bearings: high compression strength carbon black Acetal

    Spinlock PXR Cam Cleat
    Item #: 615150
  • Line Size: 8 mm to 10 mm (5/16" to 3/8")
  • Max. Working Load: 200 kg (440 lbs)
  • Precision Control of Mainsheet, Vang and Spinnaker Hoist Systems
  •  Include
    Reg. Price

    Sale Price

    Model #:
    Ronstan 55 mm Series 55 Orbit Block
    Item #: 600658
  • Single Block with Upright Lead
  • Safe Working Load: 1100 lbs
  • Maximum Line Size: 3/8"
  •  Include
    Model #:

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