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 Ronstan’s 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.