Series 50 All-Purpose Single Block
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RONSTANSeries 50 All-Purpose Single Block


In stock online.
Model # 149687 | Mfg # RF51100UPC # 9316800241101


Series 50 All-Purpose Single Block

Name Value
Ball Bearings Low Friction Bearings
Becket No Becket
Diameter 1/2 Inch or 13 mm
Direction Any
Integral Cleat No Integral Cleat
Mount Type Swivel Shackle
Ratchet Non Ratcheting
Safe Working Load 1650 Pounds
Sheave Diameter 50 mm
Type Single
Weight 4.1 Ounces

Product Overview

General application blocks provide performance and value.

A smooth and efficient block is critical to the conversation between sailor and boat—especially for hand-held control lines. Ronstan designed the Series 50 All-Purpose blocks to give dinghy and small keelboat sailors the feedback to detect subtle wind changes and sail as efficiently as possible. These light-weight blocks feature a durable, self-lubricating, UV stable acetal sheave that runs smoothly on a 316 stainless steel bearing. Fiber reinforced nylon cheeks provide rigidity and strength and are beefed up 316 stainless steel load straps. The included shackle features a pin with a low-profile head to prevent snagging on smaller lines. Get the messages your boat sends you though the lines by using efficient and smooth Ronstan Series 50 All-Purpose blocks.

This 50mm single with shackle head is versatile and can be used for a wide range of applications. Great for halyard tuners, Cunninghams, dinghy sheets and more. 

Key Features

  • Light weight blocks designed for moderate to high static and dynamic loads
  • Ideal for hand-held control lines
  • Captive lock secures swivel at 0° or 90° or left to swivel freely
  • Sliding acetal bearing on 316 stainless steel race handles high loads and maintains low friction
  • Fiber reinforced nylon cheeks to add strength while reducing weight
  • Self-lubricating, UV stable acetal sheave is strong and light-weight
  • 316 stainless steel load straps add strength
  • Ideal for:
    • Dinghy and small keelboat sheets
    • Halyard tuning systems
    • Backstay systems on dinghies and smaller keelboats
    • Boom vangs (cascade systems)

Ronstan Selection Guide

Sheave DiameterLine CompatibilityShackle Pin Diameter
20mm1/4" (6mm)1/8"
30mm5/16" (8mm)5/32"
40mm3/8" (10mm)3/16"
50mm1/2" (12mm)3/16" (1/4" for Double and Triple blocks)


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