Ronstan RF20111 Single Block with Loop Head & Becket 20mm – Series 20 Ball Bearing Pulley

The Ronstan RF20111 Single Loop Head Ball Bearing Pulley with Becket (20mm) is a compact, high-performance Series 20 block designed for efficient control line systems on modern sailing boats.

Featuring a 20mm acetal sheave running on precision stainless steel or Torlon® ball bearings, this block delivers exceptionally low friction and smooth operation, making it ideal for frequently adjusted control lines.

The loop head attachment allows flexible rigging options, while the integrated becket provides a secure tie-off point, enabling compact cascading systems and increased mechanical advantage without additional hardware.

Designed for performance and durability, the RF20111 includes a 2-axis head fitting, allowing alignment in multiple directions for optimal load handling and reduced friction.

Constructed from UV-stabilised acetal, fibre-reinforced nylon cheeks, and 316 stainless steel load components, this block is built to withstand harsh marine conditions while remaining lightweight and reliable.

With a maximum working load of 250kg and breaking load of 550kg, the RF20111 provides excellent strength in a compact form—ideal for dinghies, skiffs, and small keelboats.

Key Features

• 20mm ball bearing sheave – smooth, low-friction performance
• Loop head attachment – flexible rigging options
• Integrated becket – enables compact purchase systems
• 2-axis head fitting – improved load alignment
• High load capacity (250kg MWL / 550kg BL)
• Lightweight (~18g)
• Durable composite construction – UV and corrosion resistant

Specifications

• Brand: Ronstan
• Model: RF20111
• Series: 20 Ball Bearing
• Product Type: Single block with loop head & becket
• Sheave Diameter: 20mm
• Max Rope Diameter: 6mm
• Maximum Working Load: 250kg
• Breaking Load: 550kg
• Weight: ~18g
• Materials:
  • UV-stabilised acetal sheave
  • Stainless steel / Torlon® 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 a compact, efficient pulley with integrated tie-off for clean, simple rigging systems.

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 to create compact purchase systems without extra fittings
• Align the block correctly for maximum efficiency and reduced wear
• Pair with low-stretch Dyneema rope for best performance