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Ships within 48 hours · Estimated delivery Jul 15 - Jul 20
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For Your Every Summer RSVP, with Code: SUMMER15
Description
Ronstan Series 40 Bb Block SingleSeries 40 Ball Bearing Block Single Universal Head Sheaves Running On Acetal Or Torlon&Reg; Ball Bearings Provide High Performance & Low Friction. The 2 Stage Ball Bearing System Provides Consistent Performance Over The Full Load Range. Captive Lock Universal Head Can Be Fixed In Either Of Two Planes, Or Free To Swivel As Required. Features: Low Friction Acetal Or Torlon&Reg; Bearing System Lightweight Cheek Cut Outs For Easy Bearing Maintenance
Series 40 Ball Bearing Block - Single - Universal HeadSheaves Running On Acetal Or Torlon&Reg; Ball Bearings Provide High Performance & Low Friction. The 2-Stage Ball Bearing System Provides Consistent Performance Over The Full Load Range.Captive Lock Universal Head Can Be Fixed In Either Of Two Planes, Or Free To Swivel As Required.
Features:
- Low Friction Acetal Or Torlon&Reg; Bearing System
- Lightweight
- Cheek Cut-Outs For Easy Bearing Maintenance
- Captive Lock Universal Head
- Slotted Pin Shackle Eliminates Fouled Lines
Applications:
- Mainsheet
- Halyard
- Vang
- Spinnaker Control Lines On Off-The-Beach Catamarans, One Design Classes And Sportsboats Up To 8M(26')
Materials:
- U.V. Stabilized Acetal Sheaves
- Acetal Ball Bearings
- Impact And U.V. Resistant, Fiber Reinforced Nylon Cheeks
- Grade 316 Stainless Steel Load Strap And Head Fitting
Specifications:
Sheave Ø:40Mm(1-9/16')
Max. Rope Ø:10Mm(7/16')
Pin Ø: 5Mm(3/16')
M.W.L.:350Kg(770Lbs)
B. L.:1,000Kg(2,200Lbs)
Weight:70G(2.5Oz)
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
4.2 ★★★★★
Based on 347 reviews
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Product Reviews
★★★★★ 5
LOVE THEM!!
Size: Small, Color: (001) Black / Black / Castlerock
LOVE! These socks are so comfortable! I wear a 5 in women's and a 3 in big kid shoes. The small fit me perfectly. I see where some say they run small but I can't say that was an issue for me. They are "snug" but thats what you want with a no show sock. I feel they have support vs the ones i used to buy at Walmart. They are very soft! I am actually buying more today and throwing my other ones in the trash!
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Reviewed in the United States on February 18, 2026
★★★★★ 5
So will not write down your foot
Size: Medium, Color: (001) Black / Black / Castlerock
I love these socks. They have a little bit of gel on the top of the heel for support in your tennis shoes and so your socks don’t write down. Very good quality.
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Reviewed in the United States on May 6, 2026
★★★★★ 5
Comfy and Stay Put
Size: Medium, Color: (002) Black / Black / Halo Gray
These socks are honestly great. They’re super thin and light, so once you have them on, you kind of forget they’re even there. No bulky feeling in your shoes at all.
The best part is they actually stay on. I hate no-show socks that slide down after five minutes, and these don’t do that. The little grip on the heel really works, so you’re not constantly adjusting them all day.
They’re breathable too, which is nice if your feet run warm. They dry fast and don’t get that gross sweaty feeling. And there’s no annoying seam on the toe, so nothing rubs or feels uncomfortable.
Basically, they’re just comfy, stay put, and don’t cause problems — which is all I want from socks.
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Reviewed in the United States on January 16, 2026
★★★★★ 5
Perfect sucks
Size: Medium, Color: (001) Black / Black / Castlerock
Wonderful socks . The weight is perfect !! These do not slip when in a shoe they stay out !!
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Reviewed in the United States on April 14, 2026
★★★★★ 4
Amazing but quality changed
Size: Large, Color: (002) Black / Black / Halo Gray
Love these socks so much, been buying them for about 4 years now!! Not giving them 5 stars anymore because the quality is different and not as good, durable and thick as before.
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Reviewed in the United States on July 10, 2025