SKU: 63299332735

Ronstan Series 55 Ball Bearing Orbit Block™ - Single - Becket - Swivel Head

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Description

Ronstan Series 55 Ball Bearing Orbit Block™ - Single - Becket - Swivel HeadSeries 55 Ball Bearing Orbit Block Single Becket Swivel Head Lightweight Kilogram for kilogram of working load, BB and RT Orbit Blocks are the world's lightest. The unique orbital design allows the bearing to only be in the active areas of the floating sheave. This minimises the mass of the inactive return race and hub. Weight and bulk are further reduced in the different block configurations. The ball bearing single and becket block has a through

Series 55 Ball Bearing Orbit Block™ - Single - Becket - Swivel Head

Lightweight
Kilogram for kilogram of working load, BB and RT Orbit Blocks™ are the world's lightest. The unique orbital design allows the bearing to only be in the active areas of the floating sheave. This minimises the mass of the inactive return race and hub.

Weight and bulk are further reduced in the different block configurations. The ball bearing single and becket block has a through-sheave becket arrangement. The result? The lowest weight possible.

Multi-sheave blocks have only single intermediate cheeks and an ultra-light and efficient head arrangement. This gives a 30% weight saving advantage over the nearest competitor. Other brands just link together their single blocks. This results in unnecessary double cheeks between each sheave, held together by a heavy steel channel across the top of the block.

Highest Working Load In Its Class
The orbital ball-bearing arrangement gives the largest possible bearing race diameter. This maximises load performance. The proven Ronstan 2-stage bearing system features high compression grade acetal ball bearings and a secondary full-contact bearing. This gives minimum friction across the full working load range.

The floating sheave and bearing system is supported by a fiber-reinforced load frame. The design was computer modelled to be stress optimised. The Dyneema® Link is produced from FSE Robline SK75 fiber, which is 10 times stronger and lighter than steel, and provides the final connection from the block to the load point.

Features:
  • Ultra Lightweight
  • Low friction 2-stage Orbital ball bearing system
  • Highest working load in its class
  • Low profile and compact
  • High performance cleating
  • Swivel shackle head for unlimited block rotation
  • Stainless steel shackle head for ultimate durability and compatibility with harsh fixing points
  • Ultra low profile integrated becket


Applications:
  • Mainsheet systems on dinghies, sportsboats and small keelboats to 9M(30')
  • Spinnaker sheets on dinghies, sportsboats and small keel boats to 9M(30')
  • Halyard, Vang and Backstay application on boats to 8M(26')
  • Control line applications on larger yachts
  • Ideal use for mainsheet systems and spinnaker sheets on dinghies, sportsboats and small keel boats to 9M(30')
  • Also ideal with halyard, vang and backstay applications on boats to 8M(26')
  • Spinnaker sheets on sportsboats and small keel boats (lateral lead blocks)
  • Control line applications on larger yachts


Materials:
  • Ball bearings - High compression strength carbon black Acetal
  • Stage 2 bearing - Carbon fiber reinforced, PTFE impregnated Nylon
  • Frame/Cheeks - Toughened, glass fiber reinforced Nylon
  • Rope Link: UV stabilized, multi-strand impregmented SK75 Dyneema®
  • Sheave: Carbon fiber reinforced, PTFE impregnated Nylon
  • Head fitting: Grade 316 stainless steel.


Specifications:
Sheave Ø: 55mm(2-5/32")
Max. Rope Ø: 10mm(3/8")
M.W.L.: 500kg(1,100lbs)
B. L.: 1,000kg(2,200lbs)
Weight: 88g(3.1oz)
Manufacturer : Ronstan
Manufacturer Part No : RF55110
UPC : 9316800440405
Shipping Notes
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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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SKU: 63299332735

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4.5 ★★★★★
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Draper, US
★★★★★ 3
Mineral sunscreen stick review - poor at blending
I’m writing a review for this product as well as a number of other mineral sunscreen sticks (MSS) after testing a bunch of them—scroll down to point #6 below if you want to know which one I thought was the best. I’ve placed this exact review on every single other MSS I used. I specifically elected to go with mineral-based sunscreens—lots of talk on the environmental effects of the other sunscreens (not sure how much of this is actually true, but I’m willing to avoid the non-mineral sunscreens given the minimal investment on my part). Here are a few important points about this review: 1. No one paid me to write this review. I put down my own $140 to get all 13 of these MSSs. I just wanted to find the best one by limiting as much bias as possible. Yes, my wife definitely gave me the you’re-crazy-but-I-guess-I’m-stuck-now look. 2. Quick sunscreen tutorial. Most dermatologists say we should try to get an SPF of 30+. Each 1% of zinc counts for 1.6 SPF, so to hit SPF 30, your zinc has to be 18.75%+. Each 1% of titanium counts for 2.6 SPF, so a combination of zinc and titanium could get you to SPF 30 as well. Titanium apparently isn’t good enough to block UV-A (cancer causing and photo-aging) light on its own, so you must add zinc to it. I calculated the SPF based on the stated zinc and titanium percentages on the label and these calculations were usually different from the quoted SPFs (they might be adding more SPFs from other ingredients, but I can’t say for sure). Nine of the 13 MSSs had calculated SPFs 30+. Only 4 of the 13 had a calculated SPF greater than or equal to the label SPF. 3. Because I can’t judge cancer prevention or aging blockade in the short term, avoiding burns and eye irritation are the most important immediately observable elements of an MSS. Every MSS I tested did equally well in burn avoidance and eye irritation avoidance. 4. It should be noted that I’m not Caucasian, I’m South Asian. If you don’t know what that is exactly, Wikipedia it or watch some Russell Peters standup comedy (his old stuff, not his new stuff). My skin color is probably similar to that of Benjamin Bratt (mind you, we’re talking about his skin color only… I’m not even in the same galaxy of overall looks as he is, much to my wife’s chagrin). The ability of a white-colored MSS to blend is crucial for me. And yes, even brown people like me need sunscreen. It would absolutely suck for me as a South Asian to have a higher risk of heart disease, diabetes, and hypertension, skillfully dodge those bullets with diet and exercise and luck, only to get taken out by skin cancer. 5. I like most scents. It seems like so many things are going unscented now—an MSS that is truly unscented is okay, but a lot of things labeled “unscented,” actually have an odd, unpleasant (sort of like bad oatmeal) smell to them. The scent score is logged as a “3” if it’s truly unscented, a “5” if it has a great scent, and a “1” if it smells bad. 6. Here’s the final conclusion. Only 3 of the 13 MSSs I tested had the following combination of characteristics: calculated SPF 30+, smell score 3+, and blend score 4+. These top three were: Neutrogena Sheer Zinc, Aveeno Positively Mineral, and Blue Lizard. When you factor in cost, it’s a no-brainer—Neutrogena and Aveeno were only half the cost of Blue Lizard. Therefore, my two winners (tied for first place) are Neutrogena Sheer Zinc and Aveeno Positively Mineral. Honorable mention for Blue Lizard—twice as expensive as the others, but might be slightly easier to maneuver on your face given the smaller size stick (this is a stretch compliment for Blue Lizard—I think NSZ and APM are just better). Hope this helps you select your next mineral sunscreen stick! A^2
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Reviewed in the United States on July 12, 2020
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Maria Eugenia vivas alba
Lake Worth, US
★★★★★ 5
Muy práctico
Este protector solar es muy bueno es orgánico y a pesar q es pequeño rinde mucho y protege mucho es muy práctico usarlo en barra
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Reviewed in the United States on February 24, 2026
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Angela C
Dallas, US
★★★★★ 5
Perfect for the melanin-less crowd!
Style: SPF 15, Size: 8 Fl Oz (Pack of 1)
This is my go to brand. I’m pasty white and burn easily, but not with this! It’s long lasting and smells great too!
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Reviewed in the United States on June 5, 2026
B
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benjamin bannister
Birmingham, US
★★★★★ 5
Good For Faster Tanning
Style: SPF 15, Size: 8 Fl Oz (Pack of 1)
This is a terrific sunscreen for those looking to tan faster. It's not as low as 8 SPF, or as high as the minimum recommended 30 SPF, but it'll get you darker faster. Apply this 15 minutes before going in the sun, and reapply every two hours. As someone who recently went to Hawaii and got 2-3 hours of sun every other day for two weeks, reapplying is absolutely crucial. We went once and reapplied after three hours, and that gave us some pain. Not as much pain as not reapplying at all, but it definitely taught us to reapply no matter what, if you are in the sun. Overall, this applied cleanly and protected our skin about 93%. And 93% is better than not wearing any sunscreen at all.
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Reviewed in the United States on September 8, 2025
M
Verified Purchase
Marjorie E. Wood
Carnegie, US
★★★★★ 5
Hawaiian Tropic for this Florida girl!
Style: SPF 15, Size: 8 Fl Oz (Pack of 1)
Hawaiian Tropic Sunscreen has been my go-to for lotions and sunscreens for over 50 years! I love the fragrance, plus the offerings of oils, lotions and sprays. Purchasing from Amazon always guarantees fast deliveries and the best prices.
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Reviewed in the United States on March 29, 2026

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