Series 55 Orbit BB Upright Lead Block
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RONSTANSeries 55 Orbit BB Upright Lead Block


In stock online.
Model # 8738684 | Mfg # RF55171UPC # 9316800373499


Series 55 Orbit BB Upright Lead Block

Name Value
Becket No Becket
Diameter 3/8 Inch or 10 mm
Direction Any
Integral Cleat No Integral Cleat
Mount Type Mechanical Fasteners
Ratchet Non Ratcheting
Safe Working Load 1100 Pounds
Sheave Diameter 2 5/32 Inches or 55 mm
Type Single Upright
Weight 3.2 Ounces

Product Overview

Ronstan’s high-performance Series 55 Orbit BB Blocks incorporate unique bearing systems, super light, all-composite materials, innovative head fittings and a sleek design for the highest strength-to-weight ratio available. Precision design provides the optimum number of ball bearings in critically loaded areas, eliminates them in inactive areas and reduces ineffective mass, creating the 2-stage bearing system for durability and low-friction performance. The use of a flexible Dyneema® rope link is a product of trends in grand prix ocean racing and provides a more flexible, lighter weight and lower-profile solution than traditional shackles. It can be set at a 0- or 90-degree orientation, provides stress-free articulation without allowing the block to over-rotate, and is locked in place with a security clip that doesn’t require tools to fit. 
  • Sheave: Carbon-fiber reinforced, PTFE-impregnated engineered nylon
  • Bearings: High-compression–strength carbon black acetal; Stage 2 bearing: Glass fiber-reinforced, MoS2-impregnated engineered nylon
  • Cheek material/finish: Toughened glass fiber-reinforced nylon


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