• One-piece low‑friction double block with integrated swivel head
• CNC-machined hard black anodised & Teflon-coated aluminium frame
• Equipped with two 50 mm composite fibre sheaves and HR stainless swivel shackle
• No assembly pins or screws—lightweight yet strong design

The Antal OPF 50 mm Double Swivel Block (Model 00504) is designed for demanding sail-handling applications where strength, smooth operation, and easy handling are essential. It features two 50 mm composite fibre sheaves running on a stainless-steel hub within a one-piece hard black anodised aluminium frame. With composite bearings and Delrin side-ball bearings, this block offers ultra-low friction and high load capacity without needing lubrication.

At the top, a high-resistance stainless steel HR swivel head shackle enables three locking positions—swivel, longitudinal, and transversal—offering maximal alignment and flexibility. The resilient frame eliminates standard assembly pins and screws, making the block extremely lightweight (184 g) yet capable of handling a substantial 600 kg Safe Working Load. It’s an ideal choice for racers and cruisers who demand performance and durability in harsh marine environments.

Specifications
Sheave Diameter: 50 mm × 2
Line Size (Max): 10 mm
Safe Working Load (SWL): 600 kg (1763 lb) :contentReference[oaicite:1]{index=1}
Weight: 184 g (6.49 oz) :contentReference[oaicite:2]{index=2}
Frame Material: Hard black anodised aluminium, Teflon-coated, one-piece
Sheave Material: Composite fibre resin on stainless hub with Delrin side bearings :contentReference[oaicite:3]{index=3}
Swivel Head: HR stainless steel block shackle with 3-position locking :contentReference[oaicite:4]{index=4}
Part Number: 00504 / ANT00504

The Antal OPF 50 mm Double Swivel Block is an essential piece of deck and halyard hardware for sailors who demand high strength, low friction, and intelligent alignment in a compact, minimal-maintenance package.