Ronstan RF20100 Series 20 Single Block 20mm with Shackle Head

The Ronstan Series 20 single block with shackle head delivers high-performance ball bearing efficiency for dinghy and small keelboat sailors who demand precise feedback from their control lines. This lightweight 20mm block features an innovative two-stage bearing system that maintains smooth, low-friction operation under both moderate and high loads.

Two-Stage Bearing System:

At the heart of the RF20100 is Ronstan's unique dual bearing design. Acetal ball bearings provide exceptional efficiency under moderate loads, delivering the sensitivity needed to detect subtle wind changes. As forces increase, a plain acetal bearing running on a stainless steel race takes over, preventing ball bearing distortion while maintaining impressively low friction.

Durable Construction:

• UV-stable acetal sheave combines strength with light weight for long-lasting performance
• Fiber-reinforced nylon cheeks add rigidity while minimizing overall weight
• 316 stainless steel load straps provide enhanced strength where it matters most
• Included shackle features low-profile pin head to prevent snagging on smaller diameter lines

Ideal Applications:

• Dinghy sheets and control lines
• Halyard tuning systems and Cunninghams
• Backstay systems on dinghies and smaller keelboats
• Boom vangs and cascade systems

Specifications:

• Sheave diameter: 20mm
• Compatible with 1/4" (6mm) line
• Shackle pin diameter: 1/8"
• Designed for moderate to high static and dynamic loads

The RF20100 is a versatile block perfect for sailors who need smooth operation and reliable performance in hand-held control line applications.