Quite simply, Ronstan Ratchet Orbit Blocks™ have the highest holding power available. The sophisticated NC-machined sheave features Generation 2 of our patented sheave cross-hole geometry. Its holding power is up to 21:1, almost double that of our nearest competitior. The unique sheave design has 12 gripping faces which directly resist loaded line movement. Traditional designes have only 8 faces with an angled resistance to line movement. Our Generation 2 design has straight resistance faces which both distribute the load and minimise rope wear. These faces are offset from the radial line, to draw the rope down into the gripping area when under load. Now you can enjoy the flexibility of setting up your ratchet blocks to suit yourself. With the automatic models, the ratchet mechanism engages when load is applied, but switches off when it's released. This lets the sheet run out smoothly and freely which is great for rapid easing of the sheet and for gybing asymmetric spinnakers.