Skip to product information
1 of 1

Ronstan

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

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

SKU:55256

Regular price $59.51
Regular price Sale price $59.51
Sale Sold out
Shipping calculated at checkout.

Low stock

Quantity
  • Genuine brand-name parts
  • Ships from US warehouse
  • 30-day returns

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)

Brand Ronstan
Manufacturer part number RF55110
UPC / GTIN 9316800440405
Weight 0.21 lb
Category Marine & Boating
Condition New — genuine brand-name product
Genuine brand-name product, full manufacturer warranty. Ships from the closest US warehouse — normally within 1–3 business days. Questions before you order? Send us the manufacturer part number above and we’ll confirm. 30-day returns on unused items.

Shipping & delivery

Orders ship from the distributor warehouse closest to you, normally within 1–3 business days of purchase. Standard ground delivery takes 3–7 business days in the continental US; expedited options are shown at checkout. Oversized items (bumpers, running boards, large tonneau covers, some marine equipment) ship LTL freight — we contact you to schedule delivery and a signature is required.

Returns & warranty

Unused, uninstalled parts in original packaging can be returned within 30 days of delivery. A restocking fee of up to 20% may apply depending on the product and supplier, and return shipping is the buyer’s responsibility unless the item arrived defective, damaged or incorrect. Every product carries the full manufacturer warranty. Contact us with your order number to start a return.

Fitment & part numbers

Verify fitment with the manufacturer part number shown above and your vehicle’s year, make, model and trim. If the listing says “Fits select…”, confirm your exact application before ordering. Not sure? Send us your VIN and the part number and we’ll check it for you.

View full details