Ronstan Series 30 Ball Bearing Orbit Block - Cheek. 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 fiber-reinforced composites in the block head cleat arms and beckets. Specifications for Ronstan Series 30 Ball Bearing Orbit Block: Manufacturer: Ronstan Color: Black Package Contents: Ronstan Series 30 Ball Bearing Orbit Block Ronstan RF35151: Series 30 Ball Bearing Orbit Block - Cheek