The Ronstan Core Blocks were developed with a low-friction, two-stage ball bearing system, revolutionising the concept of conventional sailing blocks. The first stage is suitable for moderate loads, while stage two is able to support considerably heavier loads. Where deformation of the ball bearings would result in increased friction, a sliding, full-contact bearing takes on the load. This solution reduces friction by up to 50 per cent, making these blocks an innovative and functional marine product.