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Ships within 48 hours · Estimated delivery Jul 16 - Jul 21
For Your Every Summer RSVP, with Code: SUMMER15
Description
Ronstan Series 75 Core Block - SingleSeries 75 Core Block Single Core Blocks are a true all round solution. A tuned 2 stage bearing system 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. Acetal sheave, alloy cheeks and stainless fixings complete the durable package. For reliability and a long service life, these blocks are the right choice for sheets, halyards and
Series 75 Core Block - SingleCore Blocks are a true all round solution. A tuned 2-stage bearing system 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. Acetal sheave, alloy cheeks and stainless fixings complete the durable package. For reliability and a long service life, these blocks are the right choice for sheets, halyards and control line applications for cruising and racing.
Universal Bearing
Dynamic and high static load performance
The Ronstan Universal Bearing incorporates our proven 2-stage bearing system
Stage 1 - Under moderate loads, Acetal ball bearings ensure minimum friction.
Stage 2 - Under heavy loads, where deformation of ball bearings alone would result in increased friction, a sliding Acetal bearing on a polished stainless steel race takes over, maintaining low friction performance.
Additionally the ball bearings are configured to act as a thrust bearing between the sheave and cheeks, 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 cheek blocks.
Alloy Cheek Plates
Block cheeks are manufactured from the highest quality alloy for maximum strength. Material optimisation and the cut-away design minimises weight and allows easy fresh water rinsing of salt and debris from the bearings. Cheek design has been further styled with flaring at the block throat and reduced gap between the cheek and sheave, minimising rope wear.
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 316 stainless steel.
Features:
- Class leading performance and sleek, contemporary styling
- Excellent dynamic and high static load performance
- Less than half the friction of the nearest competitor
- Universal head with full 3-axis articulation
- Head posts can be locked at 0 or 90 degrees, by using a 2.5mm Hex/Allen Key
- Central hub hole can be used as a becket take-off or tie-up point
Applications:
- Ideal for mainsheet, halyard and spinnaker sheet applications on boats to 14M (46')
- Various control line applications on larger yachts
Materials:
- Sheave: U.V. stabilized Acetal
- Cheek body: Aluminium Alloy
- Ball Bearings: High compression strength carbon black Acetal
- Shackle, head post & hub: Grade 316 stainless steel
Specifications:
Sheave Ø: 75mm(3")
Max. Rope Ø: 14mm(9/16")
Pin Ø: 8mm(5/16")
M.W.L.: 1,500kg(3,300lbs)
B. L.: 3,000kg(6,600lbs)
Weight: 354g(12.5oz)
Manufacturer : Ronstan
Manufacturer Part No : RF74100
UPC : 9316800413225
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
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]
- Please click here for more details>>> Return & Exchange Policy
4.9 ★★★★★
Based on 9 reviews
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Product Reviews
★★★★★ 1
Horrible Product, Even Worse Packaging!
DO NOT BUY THESE! These are junk. Cheap wood - like balsa. Poorly packaged - no protection between wood and packaging. Crap experience, lesson learned!
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Reviewed in the United States on January 7, 2026
★★★★★ 3
Cute tall shelves but not depth enough!
These are nice, but although they aren't depth enough from the wall. They are no bigger than 2.5-3 inches depth. If you have photos or any other narrow items, you'll be perfectly happy. But for books they are not good at all. Unfortunately I returned them.
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Reviewed in the United States on July 21, 2025
★★★★★ 3
Misinformed dimensions
This product misinformed me of size. It’s 47.235” in length not 48” as advertised. This is just another means of manufacture cheating customers with false information. I did not return as I was just moving into home. I was also in a hurry to finish the installation since I bought three of these not knowing the truth. You can make your own choice but I needed 48” and paid for 48” and got shorted. I used the shipping box to make an template to install brackets that manufacture did not provide.
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Reviewed in the United States on October 4, 2025
★★★★★ 1
Terrible for the money
I purchased 2 sets…for the money I highly suggest going to an actual store to purchase…very low quality and looks horrible…I don’t want a replacement which was all that was offered…not happy
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Reviewed in the United States on February 16, 2026
★★★★★ 3
One out of the four shelves was badly bowed
Exactly what I was looking for but the reason for only three stars is thatone out of the four shelves is extremely bowed, but I only needed three so I just kept them. The quality on the other three is good they are a lightweight wood and anchored to the wall. Well, they seem pretty solid.
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Reviewed in the United States on January 3, 2026
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