New Barton Block Range Series 1: 30 mm Blocks A strong, lightweight range of blocks for use on dinghies and dayboats or as lead blocks on larger craft. Plain bearing blocks Barton plain bearing blocks have a precision moulded acetal sheave running on a large diameter brass bearing, ensuring free running under the highest of loads. Ball bearing blocks With our unique super-low friction ball race systems, featuring acetal sheaves and delrin ball bearings, running on a large diameter centre boss. This allows us to fit more load-bearing balls, which ensure extremely low friction performance, even under high loads. Important note - break loads Where break and safe working loads are stated, it is assumed that all sheaves are evenly loaded as in a purchase tackle. Uneven loading, or loading of one sheave in a double or triple block, will severely affect strength quoted. If unsure, please seek further assistance. Maximum rolling load on ball bearing blocks is the maximum free running load before ball bearings will distort.