Ronstan Series 75 Core Block - Single [RF74100]
SKU: 24372248717

Ronstan Series 75 Core Block - Single [RF74100]

Sale price$138.47 Regular price$153.85
Save 10%

Shipping Estimate
USA
  • USA
  • CAN

Ships within 48 hours · Estimated delivery Jul 8 - Jul 13

Promo Codes Available:

For Your Every Summer RSVP, with Code: SUMMER15

Description

Ronstan Series 75 Core Block - Single [RF74100]Series 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™ - 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 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)

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: 24372248717

Discover Niche Categories That Outsell

Top-Converting Item to Boost Your Average Order

4.5 ★★★★★
Based on 781 reviews
Sort
Highest Rating
Newest First
Oldest First
Product Reviews
G
Verified Purchase
Greg from MidW
Louisville, US
★★★★★ 3
Does the job but dangerous to walk with!
Does the job but dangerous to walk with: foot is sliding inside the sock if the foot was treated with cream or lotion prior. It is uncomfortable to sleep with but a necessary hurdle to heal your heels!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 24, 2025
T
Verified Purchase
Texgurl
Houston, US
★★★★★ 4
Does the trick
Bought it with urea cream for my senior dad who was diabetes. Careful with it, it will tear
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 6, 2026
A
Verified Purchase
Amazon Customer
Port Orchard, US
★★★★★ 5
The really work!
Bought these or a friend with severely dry cracked feet. The change was significant and immediate. They wore them around the house for a day and that night they could already feel the difference.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 12, 2026
L
Lina
Port Orchard, US
★★★★★ 5
Fabulously bizarre and effective
These silicone socks have to be the strangest item I have ever ordered from Amazon. However strange they are, I was pleasantly surprised with them. My order came with two pairs, and I took one pair out to wash before use. I laughed at handling them then because they were a cross between hospital socks and leftover mannequin skin…trippy. The socks dried fast, so I put on foot lotion and put the socks on. The socks are beige skin tones that cover the entire foot up to the ankle, basically booties. The silicone is very soft and makes putting on and taking off the socks easy. They are also surprisingly easy to walk around in because the bottoms have grips, again, like hospital socks. I walked on tile, hardwood, and carpet with no slipping. The booties also stayed in place with no issues. I was concerned my feet would sweat, but that didn't happen. I was able to wear them for 3 hours without sweaty feet. When I took them off, my feet were a lot more soft than before or if I had used regular socks. For reference, my feet are not terrible, but the skin around my toes is dry and peeling from my picking(gross, I know). The socks I got are a size large, which worried me because they are big, but the site said for my shoe size (9) that's what I should order, and they were right. They are the perfect size and stretchy for room. I can't believe how cool and well-thought-out these socks are, on top of working. Honestly, these are among the top 20 favorite items I've ordered from Amazon. They may look incredibly strange, and they are, but they work wonders.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 5, 2025
A
Verified Purchase
Amazon Customer
Massapequa, US
★★★★★ 3
Not well made
I have used these for 2 weeks now and one of them has a hole in the sole... I won't ever buy them again
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on July 15, 2025

recommand products