SKU: 5750437443

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

Sale price$64.48 Regular price$71.64
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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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4.0 ★★★★★
Based on 22 reviews
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Product Reviews
M
Verified Purchase
MARY A ALCALA
Pawtucket, US
★★★★★ 5
Very, very soft and cushiony that I can feel even thru the fitted sheet .
Size: King, Style: 1 Green
Very well packaged. Box was very heavy, but once I got thr shrink wrapped package opened, it inflated on its own. It is a perfect fit. Although it isn't thick, it is extremely soft and my back and hip feel better (arthritis and sciatica). I plan on getting a memory foam pad to put underneath, but for now, I am reasonably pleased. The quality was so good, I decided to keep it instead of going thru the trouble of repacking it.
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Reviewed in the United States on May 25, 2026
C
Verified Purchase
Carolina Álvarez
Phoenix, US
★★★★★ 5
Soft & Durable Mattress Protector
Color: 1 Gray, Size: Queen, Color: 1 Gray, Size: Queen
Excellent mattress cover. The fabric feels soft and comfortable while providing great protection for the mattress. It has an elegant design that gives the bed a clean and modern look. It fits well, is easy to put on, and stays in place. Great value for the price. Highly recommend!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 31, 2026
H
Verified Purchase
HandyAndy
Battle Creek, US
★★★★★ 5
Nice protector cover, quiet and comfy - best for THICK mattresses
Color: 3 Navy Blue, Size: Full
I liked this pad immediately as fabric cover has nice quilting (just slightly puffy), and touch feel and feels substantial enough to hold up over time. I’ve ordered a few different brands of these and they were crappy, insubstantial pads I did not think would hold up to more than a couple washings. My biggest complaint and it’s due to my own lack of experience buying these in the new world of skillions of mattress thickness choices is that (A) the side panels / elastic pockets are HUGE and will never be secure on anything thinner than a 12” (or thicker!) mattress; and (B) I thought I was buying an ENCASEMENT cover pad which this is not. I’m blaming that on Amazon because I specifically input “encasement” in the search and their F’ing search algorithm does whatever the heck it wants and if you’re not paying nit-picky attention you get stuff you don’t want. (Or you waste time sorting out the ones you didn’t want to see in the first place!) That said I am seriously considering keeping this (depending on late arrivals of competing covers) as I’m certain this will be comfortable and as quiet as these waterproof covers get. It’s a nice cover. UPDATE: it’s a couple weeks later and I’m reporting I did keep it and am happy to have done so. It installed more securely than anticipated and is as comfortable as I thought it would be. I’ll try and update again when I have time to resize pics and show how much my cat enjoys it too:) UPDATE#2: in review I noticed that the 1* reviews were on about nasty liquids leaking through - I haven’t had any large scale events to gauge but I can see how those reviews could be valid. I should report out of EVERY type of these “nice” noiseless “waterproof” pads I’ve got I think every one of them probably could have the same fault. In other words though I use and really like this cover I also purposely use an encasement style mattress protector (you know the put it in a bag w/zipper kind and a pain in the a** to do so kind) to avoid the complaints in the 1* camp. These mattresses are just too costly and spongelike to NOT protect them completely so I appreciate their frustration that things leaked for them. In my choice to keep this I did so because a) it most probably is pretty waterproof & is definitely quiet & comfy; b) it’s pretty easily washable; and c) because most of the encasement protectors are of more “crinkly” material than this (at least the ones I’ve seen so far - maybe the super expensive ones have figured out how to be perfectly waterproof without crinkle) and by using this nice top protector I put a layer on top of the crinklier encasement and everything just ends up much better with no noticeable crinkle. Figured I say this to help detail 1* vs. 5* because right!? how can one thing be so great and when you turn around then be so terrible… just sayin. (& I did not change my 5* rating😎)
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Reviewed in the United States on March 16, 2026
T
Verified Purchase
Thomas W.
Lake Worth, US
★★★★★ 5
⭐⭐⭐⭐⭐ Excellent Protection and Comfort — A Mattress Protector That Really Works!
Color: 3 Navy Blue, Size: Full
The BEDLORE Waterproof Mattress Protector, Full Size Mattress Pad with Deep Pocket (6″–15″) has been a fantastic upgrade to my bed setup. If you’re looking for reliable protection without sacrificing comfort, this protector delivers on every promise — and then some. 🛡️ True Waterproof Protection This mattress protector does exactly what it should — it protects. Whether it’s accidental spills, pet messes, or everyday body sweat, the waterproof barrier keeps everything from reaching your mattress. I’ve tested it with a few wet spills, and the liquid beads right up on the surface, giving me peace of mind that my mattress will stay fresh and clean for years. 🛏️ Soft and Comfortable Sleep Surface Unlike some protectors that feel stiff or noisy, the BEDLORE pad is soft, quiet, and comfortable. You barely notice it’s there, and it hasn’t changed the feel of my bed at all — it just adds protection while letting the mattress feel like my mattress. Sleeping on it feels smooth and cozy rather than plastic or crinkly. 📏 Deep Pockets Fit Perfectly The deep elastic pocket is one of my favorite features. It securely fits my mattress, which is on the thicker side, and stays in place even with nightly tossing and turning. The coverage from 6″ to 15″ means it fits almost any standard full mattress comfortably without slipping off or bunching up. 👍 Breathable & Quiet Despite being waterproof, this protector remains breathable, so I don’t wake up feeling too warm or restricted at night. It’s just the right balance — protecting without interfering with airflow or comfort. 💪 Easy to Care For Machine washing and drying are a breeze — it comes out clean and stays soft after every wash. I appreciate that it retains its shape and waterproof performance even after multiple washes. ✅ Final Thoughts Overall, the BEDLORE Waterproof Mattress Protector is a well‑made, comfortable, and highly effective mattress pad that offers great protection without the unwanted stiffness some other protectors have. It’s a smart way to preserve your mattress investment while still enjoying a comfortable night’s sleep. I’m very happy with it and would absolutely recommend it! ⭐⭐⭐⭐⭐
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 2, 2026
M
Verified Purchase
Mimi in Maine
Phoenix, US
★★★★★ 5
Excellent waterproof mattress cover find
Color: 5 Beige, Size: Queen
Good quality. Backing is waterproof with quiet material being such. Top cover is soft cotton which is hard to find. Followed proper washing & drying per tag instructions results were good. Em confident it will have longevity in quality. Also, a perfect regular queen mattress fit.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 6, 2026

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