SKU: 5750437443

Ronstan Series 45 Core Block™ - Single - Swivel Shackle Head

Sale price$64.48 Regular price$71.64
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Ships within 48 hours · Estimated delivery Jul 20 - Jul 25

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Description

Ronstan Series 45 Core Block™ - Single - Swivel Shackle HeadSeries 45 Core Block Single Swivel Shackle Head 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,

Series 45 Core Block™ - Single - Swivel Shackle Head

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 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.

Features:
  • High dynamic and static load capacity
  • Efficient 2-stage 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


Applications:
  • Ideal for mainsheet, halyard and spinnaker sheet applications on boats to 10M (33')
  • Various control line applications on larger yachts
  • Alloy sheave models are available for use with wire


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: 45mm(1-3/4")
Max. Rope Ø: 12mm(1/2")
Pin Ø: 5mm(3/16")
M.W.L.: 700kg(1,540lbs)
B. L.: 1,400kg(3,090lbs)
Weight: 104g(3.6oz)
Manufacturer : Ronstan
Manufacturer Part No : RF44100
UPC : 9316800466153
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. 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
SKU: 5750437443

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JCMIV63
Louisville, US
★★★★★ 5
Cushioned, comfortable, stylish and a rubber sole!
Size: 10, Color: Brown
These shoes check multiple boxes for me, comfortable, cushioned, rubber sole and stylish. As my feet grow old and worn out, I'm on a constant search for comfortable, cushioned shoes that are suitable for work and dressier occasions. I have tried many expensive shoes that look great but either lack cushioning, arch support and or comfort. One of the nice things is these shoes have a rubber sole, where most cushioned shoes have the foam soles which are great, but they tend to lack grip particularly when its damp/wet. They have average arch support, but the insole is removable and I put my own cushioned arch support. Love these!
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Reviewed in the United States on April 6, 2026
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DDD Projects
Lake Worth, US
★★★★★ 5
OG Style
I am a big fan of Bruno Marc shoes. Over the years they have provided comfortable and affordable boots and shoes. These blue, tan and white soled dress sneakers are no exception. They have a nice finished look that makes them both causal and dressy. The lightweight style is still warm enough for colder mid-west winters. The box of the toes is wide and comfortable. The insole is well padded and a pleasure to wear. This is another fine pair of shoes to add to my collection and yours.
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Reviewed in the United States on January 14, 2026
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Premium Reviews
Bozeman, US
★★★★★ 5
Must buy: Comfort + Casual + Well Made / Ventilated
Size: 8, Color: Brown
Just buy it! I have put in roughly 15,000 steps in this shoes in 10 days and I can't believe how comfortable they are after this much rough use in short amount of time. I highly recommend this shoes to anyone looking for comfort in casual style.
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Reviewed in the United States on May 4, 2026
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William W.
Waukegan, US
★★★★★ 5
WIDE Dress Shoes With SUPPORT
Size: 10.5, Color: Brown
I've seen dress shoes and worn dress shoes before, but these are simply the best dress shoes I've ever worn my entire life. 99% of dress shoes have the same problem, they have the thinnest little soles that offer no support. BRUNO MARC HAS SOLVED THE PROBLEM. These dress shoes not only support wide feet like mine who historically have had and still have little support in the market, but Bruno Marc has wide options that fit perfectly, and the support with the thick foam sole is so needed and awesome. I had a pleasant surprise putting these things on and there being some tactile grip enhancers inside the shoe so you can feel the shoes better and get a little tickle / massage while you're at it. These things are dripping with style, easy to wear, and while they might look firm on the outside, on the inside the shoe just has such a nice flexibility and foamy feel, the top where the top of your feet feel the roof of the shoe, it has such perfect ooey gooey support I can't believe it. The outside sole also has this neat tactile feel. The durability looks good and feels good for now.
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Reviewed in the United States on September 28, 2025
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Amazon Customer
Port Orchard, US
★★★★★ 5
Great Shoes
Size: 10, Color: Cognac
Love these shoes super comfortable and look great. Everyone asks me where I got them.
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Reviewed in the United States on May 20, 2026

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