Description
40mm Carbo Air Double Swivel Block with Becket
Low-friction Carbo Air blocks are lightweight, strong, reliable—and affordable. Companions to the popular Harken Black Magic block line, these small, compact blocks have very high working loads for safe, easy trimming.
Specifications:
- Sheave Ø (mm)40 mm
- Sheave Ø (in)1 9/16 in
- Maximum line Ø (mm)10 mm
- Maximum line Ø (in)3/8 in
- Maximum working load (kg)440 kg
- Maximum working load (lb)970 lb
Quick Guide (pdf)

![Harken 40mm Carbo Air Double Swivel Block w/Becket [2639]](https://www.bestmarinebattery.com/wp-content/uploads/2026/08/harken-40mm-carbo-air-double-swivel-block-w-becket-2639.webp)

![Ronstan Series 30 Ball Bearing Block - Single - Loop Top [RF30101]](https://www.bestmarinebattery.com/wp-content/uploads/2026/08/ronstan-series-30-ball-bearing-block-single-loop-top-rf30101.webp)


![Ronstan Wire Block - Tubular Rivet Head w/Nylatron Sheave - 25mm (1") Sheave Diameter [RF418]](https://www.bestmarinebattery.com/wp-content/uploads/2026/08/ronstan-wire-block-tubular-rivet-head-w-nylatron-sheave-25mm-1-sheave-diameter-r.webp)
![Ronstan Series 50 All Purpose Block - Double [RF51200]](https://www.bestmarinebattery.com/wp-content/uploads/2026/08/ronstan-series-50-all-purpose-block-double-rf51200.webp)

![Ronstan Series 40 Orbit BB Quin Block w/Swivel Shackle [RF48500]](https://www.bestmarinebattery.com/wp-content/uploads/2026/08/ronstan-series-40-orbit-bb-quin-block-w-swivel-shackle-rf48500.webp)