Ronstan Series 30 Ball Bearing Blocks Single Becket Option Lashing. 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. Specifications for Ronstan Series 30 Ball Bearing Block Single Becket Option Lashing: Manufacturer: Ronstan Color: Black Package Contents: Ronstan Series 30 Ball Bearing Block Single Becket Option Lashing Ronstan RF35109HL: Series 30 Ball Bearing Blocks Single Becket Option Lashing