Ronstan Series 25 Ball Bearing Orbit Block with Becket and Lashing - RF28109

Series 25 Ball Bearing Orbit Block - Lashing

Single sheave ball bearing block with becket and lashing head.

The Series 25 Ball Bearing Orbit Blocks deliver superior strength, reduced weight, and exceptional performance for high-demand dinghy and small boat applications.

Designed with competitive sailors and performance boats in mind, these compact 25mm blocks are engineered to achieve the highest possible strength-to-weight ratio. Featuring Ronstans renowned high-compression strength acetal bearing system, the Series 25 BB Orbit Blocks are a lightweight yet durable solution, ideal for control line systems such as mainsheet and spinnaker sheet turning blocks, cunninghams, and cascading vangs on dinghies up to 4 metres.

Each block has a stainless steel hub for versatile lashing attachments and through-sheave becket functionality, making them adaptable to a wide range of rigging setups. The hub accommodates up to 4mm (5/32) lashing and ensures maximum efficiency without compromising reliability.

Features:

• 2-stage ball bearing system.
• Suits up to 8mm (5/16) lines.
• Hollow hub for becket take-off.
• Lashing blocks suit up to 4mm (5/32) lashing.

Specifications:

• Max. Rope diameter (in): 5/16
• Sheave diameter (in): 1
• B.L. (lb): 1650
• Weight (oz): 0.5

Applications:

• Mainsheet and spinnaker sheet turning blocks on dinghies to 4m (13ft).
• Control lines.
• Cascading vangs.
• Leech lines cunninghams.

Materials:

• BB Sheave and balls: High compression strength acetal.
• Frame/cheeks: Toughened, glass-fiber-reinforced nylon.

The Ronstan Series 25 Ball Bearing Orbit Block with Becket and Lashing (Part Number RF28109) is a high-performance, lightweight rigging component designed for competitive sailors and small boat enthusiasts. Crafted with precision and durability in mind, this compact 25mm block offers an exceptional strength-to-weight ratio ideal for controlling mainsheets, spinnaker sheets, and other control lines on dinghies up to 13 feet long.

Constructed with Ronstan's renowned high-compression strength acetal bearing system, the Series 25 orbit block provides smooth operation and reliable performance even under demanding conditions. Its two-stage ball bearing system ensures minimal friction, allowing for effortless line handling and increased efficiency during racing or recreational sailing. The hollow hub design accommodates up to 4mm (5/32 inch) lashing, making it versatile for various rigging configurations and easy to adapt to your specific setup.

Designed with versatility in mind, this orbit block features a stainless steel hub that supports through-sheave becket functionality and lashing attachments, enabling secure and flexible rigging options. Whether used as a turning block for control lines or as part of a cascading vang system, this durable component maintains high performance over time. Its compact size and lightweight build—just under 1 ounce—make it an ideal choice for performance boats where weight savings are critical.

Manufactured from toughened, glass-fiber-reinforced nylon and high-strength acetal, this Ronstan orbit block is engineered to withstand harsh marine environments. It supports line diameters up to 8mm (5/16 inch), providing reliable operation across a range of sailing applications. Whether used on a dinghy or small racing boat, the Series 25 orbit block delivers superior performance, durability, and ease of installation for demanding sailing enthusiasts.

Features:

• 2-stage ball bearing system provides smooth and efficient line handling

• Suitable for lines up to 8mm (5/16 inch) in diameter

• Hollow hub design allows for quick becket take-off and versatile lashing options

• Lashing blocks support up to 4mm (5/32 inch) lashing for flexible rigging