For boats up to 8.5m/28 ft Use size 0 1 or Synchro 50mm/60mm blocks. Suitable for 6mm (1/4") control line For boats with mid-boom sheeting to 130 ft Use wih size 0 track Mainsheet car with low friction slide rods and shackle, with pinstop plunger to lock car in place and one integral control sheave for 1/4" line