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Ronstan Series 100 Core Block, Single, Universal head

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Updated: April 2025

MSRP: $419.00
$356.15
(You save $62.85 )
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SKU:
RONRF104100
UPC:
9316800553266
Availability:
Y
Weight:
2.00 LBS
Shipping:
Calculated at Checkout.
Size:
100 mm
Ronstan Single Block Universal Head (RF104100).
For reliability and a long service life, these blocks are the right choice for sheets, halyards and control line applications for cruising and racing.
Ronstan Series 100 extend the "true all round solution" mandate of the Ronstan Core BlocksS™ up in to the 16m (50 footer) boat range. The self-lubricating, heavy -duty bearing system provides excellent performance across the full working load range and is complimented by an integrated thrust bearing feature providing the resilience to handle high dynamic or static loads. A fibre-reinforced nylon sheave, alloy cheeks and stainless fixings complete the durable package.
> Ronstan Core Blocks Specifications

Technical Description
Series 100 Core Single Block
4 in
100 mm
3/4 in
18 mm
3/8 in
10 mm
7150 lb
3250 kg
16500 lb
7500 kg
31.8 oz
900 g

> Ronstan Core Block Series 100 Features
• High dynamic and static load capacity.
• High load bearing system.
• Ball bearings to counteract side thrust loads.
• Class leading performance and sleek, contemporary styling.
• Durable aluminium alloy cheek plates.
• Central hub hole can be used as a becket take-off or tie-up point.
• Universal head with full 3-axis articulation.
• Head posts can be locked at 0 or 90 degrees, by using a 2.5mm Hex Key.
• Ideal for mainsheet, spinnaker sheet, vang, halyard and backstay applications on boats to 16m (53ft).
> Ronstan Core Blocks Information
A balanced design approach incorporating functionality, performance and style makes the Series 100 Core Blocks™ the right choice for performance cruising or racing applications. A full contact bearing provides excellent performance across the full working load range with an integrated thrust bearing feature and the resilience to handle high dynamic or static loads. Glass Fibre reinforced nylon sheave, alloy cheeks and stainless fixings complete the durable package.

Dynamic and high static load performance. Core Blocks™ incorporate a full contact acetal bearing on a polished stainless steel race to maintain low friction performance under heavy loads. Ball bearings are configured to act as a thrust bearing between the sheave and checks, preventing the sheave from rubbing on the cheeks and causing friction when the line lead in and out of the block isn’t perfect; particularly important for foot blocks.

Universal head. The head assembly incorporates a brass bearing washer to provide smooth 360° rotation of the post and shackle. A set screw arrangement allows the head to be locked at 0° or 90°. Shackles are high quality forged grade 17-4PH stainless steel.

Aluminium alloy cheek plates. Block cheeks are manufactured from the highest quality aluminium alloy for maximum strength and hard anodised for durability and corrosion resistance. Material optimisation and the cut-away design minimises weight and allows easy fresh water rinsing of salt and debris from the bearings. The hollow hub can be used as a becket take-off or tie-up point.
> Ronstan Core Blocks Material
• Bearings: High compression strength, self-lubricating acetal.
• Head post: Grade 2205 stainless steel.
• Shackles: Grade 17-4PH stainless steel.
• Padeye: Grade 15-5PH stainless steel.
• Other fixtures: Grade 316 stainless steel.
• Shackle, post & hub: Grade 316 stainless steel.