Ronstan Series 25 Ball Bearing Orbit Block - Lashing - RF28109

Ronstan Series 25 Ball Bearing Orbit Block – Lashing – RF28109

Get lightweight, low-friction performance for your sailboat rigging with the Ronstan Series 25 Ball Bearing Orbit Block – Lashing (RF28109). Designed for dinghies and small performance sailboats, this compact single-sheave block combines a 25mm (1") sheave, 2-stage ball bearing system, and versatile lashing attachment for an outstanding strength-to-weight ratio.

The RF28109 uses Ronstan's high-compression-strength Acetal sheave and ball bearing system to provide smooth, efficient line movement while keeping overall weight to just 14g (0.5 oz.). Toughened, glass-fiber-reinforced nylon cheeks provide a strong yet lightweight frame suited to demanding sailing environments.

A stainless steel hollow hub provides flexibility for lashing attachment and can also serve as a becket take-off. The block accommodates lashing line up to 4mm (5/32") and working lines up to 8mm (5/16"), making it a versatile choice for compact control systems.

With a maximum working load of 550 lbs. (250kg) and breaking load of 1,650 lbs. (550kg), the RF28109 delivers impressive strength from a block weighing only half an ounce. Ronstan recommends Series 25 Orbit Blocks for applications including mainsheet and spinnaker sheet turning blocks on dinghies up to approximately 4m (13'), as well as control lines, cascading vangs, leech lines, and cunninghams.

Key Features

• 2-Stage Ball Bearing System: Provides smooth, low-friction line handling

• 25mm / 1" Sheave: Compact size ideal for performance sailing and control-line systems

• Lashing Attachment: Accommodates lashing line up to 4mm (5/32")

• Hollow Stainless Steel Hub: Allows versatile lashing configurations and becket take-off

• Up to 8mm Line Capacity: Suitable for rope up to 5/16" in diameter

• 550 lb. Maximum Working Load: Excellent load capacity for a lightweight 25mm block

• 1,650 lb. Breaking Load: Provides impressive strength for its compact dimensions

• Ultra-Lightweight: Weighs just 14g / 0.5 oz.

• Acetal Sheave & Bearings: High-compression-strength material provides smooth, dependable operation

• Reinforced Nylon Frame: Toughened glass-fiber-reinforced nylon cheeks combine strength and low weight

• Versatile Rigging Applications: Ideal for control lines, vangs, cunninghams, leech lines, mainsheets, and spinnaker systems

Specifications

Manufacturer: Ronstan
Series: Series 25 Orbit
Manufacturer Part Number: RF28109
Block Type: Single Ball Bearing Block
Attachment: Lashing Head
Bearing System: 2-Stage Ball Bearing
Sheave Diameter: 25mm / 1"
Maximum Rope Diameter: 8mm / 5/16"
Maximum Lashing Diameter: 4mm / 5/32"
Maximum Working Load: 250kg / 550 lbs.
Breaking Load: 550kg / 1,650 lbs.
Weight: 14g / 0.5 oz.
Sheave Material: High-Compression-Strength Acetal
Bearing Material: High-Compression-Strength Acetal
Frame/Cheeks: Toughened Glass-Fiber-Reinforced Nylon
Hub: Stainless Steel
UPC: 9316800661923

Recommended Applications

• Mainsheet turning blocks

• Spinnaker sheet turning blocks

• Sailboat control lines

• Cascading vang systems

• Leech lines

• Cunninghams

• Dinghy and small sailboat rigging

Important Load Note

The maximum working load and breaking load depend on the strength of the line used to lash the block through the central hub. Knots, splices, and stitching can reduce the effective breaking strength of the lashing system and should be considered when selecting and installing the block.