Click to enlargeRonstan Series 20 Ball Bearing Block - Single
Manufacturer: RonstanPart #: RF20100SKU: 55131
- 550 lb
- Stainless Steel
Add $75.86 more to qualify for free shipping.
Item #: 55131
Category: Outrigger Accessories
● In stock — ships fast from US warehouses
- Ships from US warehouses
- Free shipping on orders over $99
- Secure checkout — your info is protected
- Genuine marine-brand parts, not knockoffs
- 30-day returns
- Marine parts support — we know boats
Description
Series 20 Ball Bearing Block - Single Features: Low friction High static and dynamic load capacity Lightweight Precision molded Acetal sheaves running on stainless steel or Torlon® ball bearings provide high performance & low friction Applications: Dinghy control lines Dinghy Vangs Cunninghams Traveller controls Materials: U. V.
Stabilized Acetal sheaves Stainless steel ball bearings Grade 316 stainless steel load strap and head fitting Impact and UV resistant, fiber reinforced Nylon cheeks Specifications: Sheave Ø: 20mm(3/4") Max. Rope Ø: 6mm(1/4") Pin Ø: 3mm(1/8") M.
W. L.
: 250kg(550lbs) B. L.
: 550kg(1,210lbs) Weight: 20g(0. 7oz)
Specifications
| Brand | Ronstan |
|---|---|
| Part Number | RF20100 |
| EverTide SKU | 55131 |
| UPC | 9316800255504 |
| Material | Stainless Steel |
Specifications are provided by the manufacturer. Confirm fitment for your application before ordering, or contact us and we'll help.
Compare similar products
Complete your setup

Ronstan Series 20 ball Bearing Block - Triple - 2-Axis Shackle head
$45.76
Ronstan Series 20 Ball Bearing Orbit Block - Single - Dyneema Lashing - Becket Option
$15.43
Ronstan Series 30 Ball Bearing Orbit Block™ - Single - Becket - Swivel Shackle Head
$24.54
Ronstan Series 20 Ball Bearing Block - Double - 2-Axis Shackle Head
$33.71Returns & warranty
Returns are accepted within 30 dayson items that are unused and in their original packaging. Some items may be subject to a manufacturer restocking fee. Special-order items may not be eligible — if you're unsure, ask us before ordering.
Ronstan productscarry the manufacturer's standard warranty. For a warranty claim or a return authorization, see our full returns policy or contact us.
Sailing — frequently asked
- How do I size a block for my sailboat?
- Match the block to the line diameter it will carry and to the working and breaking loads of the system (sheet, halyard, control line). Makers publish load ratings and line-size ranges — choose a block whose working load comfortably exceeds the real-world load, without going so large it adds needless weight.
- What is running rigging?
- Running rigging is the moving lines that control the sails — sheets, halyards, and control lines — as opposed to standing rigging (the fixed wire that holds up the mast). Running rigging should be matched to the boat’s blocks, clutches, and winches for smooth, reliable sail handling.
- How do I maintain sailboat winches and hardware?
- Rinse with fresh water after sailing, keep sheaves and bearings clean, and periodically service winches (disassemble, clean, and re-grease per the maker’s instructions). Marine-grade stainless and good maintenance keep hardware working smoothly when loads are high and timing matters.
Customer reviews
No reviews yet — this product.
Fast shipping
Ships from US warehouses — free over $99
The right part
Marine-grade parts matched to your boat
Real support
Questions? We know boats — call or email
