Ronstan RF20212 Double Block with Becket 20mm – Series 20 Ball Bearing Pulley

The Ronstan RF20212 Double Ball Bearing Pulley with Becket (20mm) is a compact, high-performance Series 20 block designed for efficient purchase systems on modern sailing boats.

Featuring two 20mm acetal sheaves running on precision stainless steel ball bearings, this block delivers smooth, low-friction operation under both dynamic and static loads, making it ideal for frequently adjusted control lines.

The integrated becket provides a fixed tie-off point, allowing you to build compact cascading systems and achieve greater mechanical advantage without additional fittings.

A key feature is the 2-axis shackle head, which can be set at 0° or 90°, ensuring optimal alignment with load direction and reducing friction and wear on your rigging system.

Constructed using UV-stabilised acetal sheaves, fibre-reinforced nylon cheeks, and 316 stainless steel load components, the RF20212 offers excellent durability, corrosion resistance, and long-term reliability in harsh marine environments.

With a maximum working load of 350kg and breaking load of 700kg, this lightweight block delivers impressive strength for its size—perfect for dinghies, skiffs, and small keelboats.

Key Features

• Double 20mm sheaves – efficient load distribution
• Ball bearing system – low friction, smooth performance
• Integrated becket – enables compact purchase systems
• 2-axis shackle head – adjustable alignment (0° or 90°)
• High load capacity (350kg MWL / 700kg BL)
• Lightweight (~44g)
• Durable composite construction – UV and corrosion resistant

Specifications

• Brand: Ronstan
• Model: RF20212
• Series: 20 Ball Bearing
• Product Type: Double block with becket
• Sheave Diameter: 20mm
• Max Rope Diameter: 6mm
• Pin Diameter: 4.0mm
• Maximum Working Load: 350kg
• Breaking Load: 700kg
• Weight: ~44g
• Materials:
  • UV-stabilised acetal sheaves
  • Stainless steel ball bearings
  • 316 stainless steel load strap
  • Fibre-reinforced nylon cheeks

Ideal Applications

• Vang systems
• Cunningham and outhaul controls
• Traveller systems
• Dinghy and skiff rigging
• General-purpose control lines

This block is ideal where you need efficient mechanical advantage in a compact, lightweight setup.

Why Buy from Barton Marine NZ?

• Trusted NZ Ronstan supplier
• Fast nationwide delivery
• Genuine high-performance sailing hardware
• Ideal for NZ racing and cruising conditions

Pro Tip 

• Use the becket for clean, compact purchase systems
• Align the head correctly to reduce friction and extend lifespan
• Pair with low-stretch Dyneema lines for best performance