20MM BLOCK - SINGLE

Reference A2021SC

A2021SC - DYNAMIC single pulley - 20 mm multifunctional sheave diameter with swivel head - MWL = 115 kg

€40.08
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20mm Single Dynamic Block with Swivel Fork Head — Maximum Freedom of Movement

The A2020SC is our go-to low-friction, fast-rolling 20mm pulley, fitted with a swivelling fork head and threaded pin for the ultimate in rigging flexibility. Lightweight and strong, it is ideal for dinghies, windsurfing, kitesurfing and any application running smaller-diameter lines that demands constant sheave movement.

Swivel Fork Head with Threaded Pin

The fork head rotates through a full swivel, allowing the block to align freely with the line of pull from any direction. Combined with the threaded pin for secure, positive attachment, and the ability to articulate on the fitting, this head delivers the greatest possible freedom of movement of any attachment type in the Dynamic range — eliminating line twist, reducing friction and keeping the sheave running true regardless of load angle.

Dynamic Bearing System

Like all Dynamic blocks, the A2020SC features our patented twin-row stainless-steel ball bearing system running on a stainless-steel rail — delivering superior load-carrying capacity and exceptional longevity compared to conventional plastic-rail designs.

Rope-Friendly Becket

The large central rivet reduces overall block weight while providing a smooth, rope-friendly attachment point — perfect as a tie-off in cascade systems.

Frequently asked questions

What is the practical difference between a swivel fork head and a standard articulating fork head?

A standard articulating fork head (such as on the A2020F) pivots in one plane — it can tilt forward and back relative to the fitting, which handles most load angle changes effectively. A swivel fork head adds rotation around the block's vertical axis on top of that articulation, meaning the block can also rotate to follow a line that pulls from the side or changes direction horizontally. This makes the swivel fork head the better choice wherever the lead angle of the line changes in more than one plane, such as on a turning block, a multi-directional purchase system, or anywhere line twist is a concern.

Does the swivel affect the security of the threaded pin attachment under load?

No — the swivel mechanism operates independently of the threaded pin connection. The pin passes through the fork jaws and the fitting as normal, and is secured by threading it fully home regardless of the swivel position. The rotation happens within the block's own head assembly, above the pin, so the pin remains fully engaged and secure at all times. Under working loads, the threaded pin provides the same positive retention as on any fork-head block in the Dynamic range.

In which rigging applications does a swivel fork head offer a clear advantage over other head types?

The swivel fork head comes into its own in applications where the direction of pull changes in more than one axis — turning blocks at deck level, blocks on a traveller car, systems where the line can lead from varying horizontal angles, or any setup where preventing line twist is important. On a dinghy, typical examples include mainsheet turning blocks, vang systems with complex geometry, and any block mounted at a junction point between two control lines. For purely vertical or single-plane loads, a standard fork head or hook is simpler and equally effective — but wherever multi-axis movement is involved, the swivel fork head eliminates the binding and wear that would otherwise result.