Ronstan Series 55 Orbit Blocks

Ball Bearing Orbit Blocks™ boast the highest strength-to-weight ratio available.  This is achieved through all-composite reinforced polymer materials and multiple attachment options.
Their precision design provides the optimum number of ball bearings for minimum friction while weight reduction is achieved through the use of fibre-reinforced composites in the block head, cleat arms and beckets.
Applications include mainsheet systems and spinnaker sheets on dinghies, sports boats and small keel boats to 9m, Multi purchase mainsheet systems on catamarans to 8m (9518), halyard, vang and backstay applications on boats to 8m and control line applications on larger yachts.