Ronstan Series 20 Ball Bearing Block - Single

The Ronstan Series 20 Ball Bearing Block — Single is a precision-engineered pulley system designed for sailors, riggers, and marine equipment specialists who demand reliable load transfer with minimal friction. This single block is the foundation of efficient rope management systems aboard sailboats, dinghies, and tactical rigging applications. Its compact footprint and lightweight construction make it ideal for high-performance sailing where every ounce and every inch of deck space matters.

Built with precision-molded Acetal sheaves running on stainless steel or Torlon® ball bearings, this block delivers exceptional low-friction performance under both static and dynamic loads. The ball bearing design reduces resistance compared to traditional bushing blocks, allowing sailors to achieve faster sail adjustments with less physical effort. Weighing just 0.1 lbs and measuring 2 x 1 x 4 inches, the Series 20 combines durability with minimal weight penalty—critical factors in modern yacht racing and cruising applications where performance and material efficiency intersect.

Marine professionals and competitive sailors benefit most from this block when building mainsheet, jib sheet, and control line systems. The high static and dynamic load capacity ensures reliable operation during aggressive maneuvers and heavy-air sailing without compromising safety margins. Single blocks pair seamlessly with companion blocks and Ronstan fittings to create custom rigging solutions; verify rope diameter and load requirements against the Series 20 specifications before installation to optimize performance and longevity in your specific application.