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Ronstan Series 55 BB Orbit Block, Double Becket Swivel [RF55210]

Ronstan Series 55 BB Orbit Block, Double Becket Swivel [RF55210]

Regular price $96.90
Regular price $114.00 Sale price $96.90
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Series 55 BB Orbit Block, Double Becket Swivel


Kilogram for a kilogram of working load, BB and RT Orbit Blocks™ are the world’s lightest. The unique orbital design allows the bearing to only be in the active areas of the floating sheave. This minimizes the mass of the inactive return race and hub.

Weight and bulk are further reduced in the different block configurations. The ball bearing single and becket block have a through-sheave becket arrangement. The result? The lowest weight is possible.

Multi-sheave blocks have only single intermediate cheeks and an ultra-light and efficient head arrangement. This gives a 30% weight-saving advantage over the nearest competitor. Other brands just link together their single blocks. This results in unnecessary double cheeks between each sheave, held together by a heavy steel channel across the top of the block. 

Highest working load in its class

The orbital ball-bearing arrangement gives the largest possible bearing race diameter. This maximizes load performance. The proven Ronstan 2-stage bearing system features high compression grade acetal ball bearings and a secondary full-contact bearing. This gives minimum friction across the full working load range.

The floating sheave and bearing system are supported by a fiber-reinforced load frame. The design was computer modeled to be stress optimized. The Dyneema® Link is produced from FSE Robline SK75 fiber, which is 10 times stronger and lighter than steel and provides the final connection from the block to the load point.


  • 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 and compatibility with sharp fixing points
  • Ultra low profile integrated beckets
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