Ronstan Series 40 Double Becket Swivel Orbit Block

The Ronstan Series 40 Double Becket Swivel Orbit Block gives a multi-part purchase two low-friction sheaves, an integrated becket, and a swiveling shackle in one compact unit. The becket anchors the standing end while the swivel head lets the block align with the working load. Ronstan lists Series 40 Orbit blocks for mainsheets and spinnaker sheets on performance dinghies and small sportboats, with additional use in halyard, vang, and backstay systems. This double version is a natural building block for compact purchases where separate attachment hardware would add unnecessary bulk.

Both sheaves use Ronstan's two-stage bearing arrangement, combining ball bearings for easy trimming with a secondary full-contact surface for higher loads. Toughened glass-fiber reinforced nylon cheeks reduce weight compared with traditional strap-style utility blocks. The swivel shackle gives the block room to follow the tackle, while the becket remains available for the fixed end of the line. That arrangement keeps the purchase organized and makes the line path easier to inspect and service.

• Double-sheave Orbit block with integrated becket
• Swivel shackle for load alignment
• Two-stage low-friction bearing system
• Lightweight reinforced composite cheeks

This model accepts line up to 3/8 in and is rated for a 1,320 lb maximum working load with a 2,650 lb breaking load. Ronstan lists the block at about 4.6 oz, keeping it relatively light for a double block with a becket and swivel. Reeve the tackle so the becket and both sheaves share a clean, uncrossed line path before applying full load. For more double Orbit blocks and purchase-system hardware, browse more Sailing Hardware.