Ronstan Series 55 Ratchet Orbit Block - Single - Swivel Head - Auto & Manual [RF56100]Series 55 Ratchet Orbit Block Single Swivel Head Auto & Manual Automatic Ratchet Block Now you can enjoy the flexibility of setting up your ratchet blocks to suit yourself. Ronstan is the only company that offers a ratchet block with both auto and manual engagement modes. In the auto mode of the ratchet mechanism engages when load is applied, but switches off when it's released. This lets the sheet run out smoothly and freely great for rapid easing of