Pro-Ratchet 60 with Cheek AdaptorRatchet blocks feature an internal ratcheting mechanism which only allows the sheave to turn in one direction. This gives the user more control to make incremental adjustments to hand-held lines such as jib sheets, spinnaker sheets and mainsheets.Cheek Adaptor - This version comes with a cheek side plate, to allow mounting to any flat surface. Three screws are required to complete installation.Switchable - In the middle of the block is a switch that can be used, even under load, to turn the ratchet mechanism on or off. Giving you more control and feel of your control system. Extreme Hold - The Pro-Ratchet 60 features a hardwearing nylon sheave with eight V grips to give extreme holding power on all lines. For maximum performance, we recommend pairing this ratchet block with 7mm Excel Marstron Plus.