★★★★★ 4
Good fit
Worked well with no problems.
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Reviewed in the United States on February 24, 2026
Ronstan Series 40 Ball Bearing Block - Single Upright Lead - RF40171
Marsoni
M251S
Get it in 3 business days with 1 day shipping.
Friday, May 29
Ronstan Series 40 Ball Bearing Block - Single Upright Lead - RF40171Series 40 Ball Bearing Block Single Upright Lead Lead blocks are a low profile solution for leading halyards or other rig sail controls back to cleats or jammers. Precision molded Acetal sheaves running on Acetal or Torlon ball bearings provide high performance & low friction. The 2 stage ball bearing system provides consistent performance over the full load range. Applications: Typically used for halyards at the mast base. Materials: Acetal ball
Quick Dispatch:
Your Ronstan Series 40 Ball Bearing Block - Single Upright Lead - RF40171 orders ship within 1-2 business days.
Delivery Options:
- Standard: 3-7 business days
- Fast: 2-3 business days
- Express: 1-2 business days
Order Tracking:
You'll receive a tracking link by email once your Ronstan Series 40 Ball Bearing Block - Single Upright Lead - RF40171 ships.
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Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
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4.1 ★★★★★
Based on 923 reviews
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Product Reviews
★★★★★ 5
Great replacement kit
Called around for quotes to get them replaced and everyone was quoting over $2k just for bellows. Figured I’d give it a try. The rubber is good quality and feels soft. Time will tell but this is an easy job if you’re mechanically inclined. Make sure you replace the plastic water pickup fitting while you’re at it. Found mine to be cracked on disassembly and had to wait for a new one. Should be a easy 3-4 hour job if your not doing the bearing and only doing bellows
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Reviewed in the United States on August 26, 2024
★★★★★ 3
Just ok
Qualities OK, but for Marine applications might want better
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Reviewed in the United States on August 3, 2025
★★★★★ 5
Great quality
Just as described.
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Reviewed in the United States on July 22, 2025
★★★★★ 5
Bellows kit review initial inspection’s
Very good quality. The hose clamps were event the better ones you have to pay extra in most cases.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 6, 2025
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