b"Mainsail Reefing Part numbers represent hardware most commonly used.Typical boat length: ASmall Boat: 6.7 - 8.5 m (22 - 28') DMidrange: 8.8 - 10.4 m (29 - 34') BBig Boat: 10.7 - 12.8 m (35 - 42')CDiagram Small Boat Midrange Big Boat CRef. Description Part No. Part No. Part No.Dual LineA Cheek 2644 6237 3220 Dual Line: This dual-line system is common on boats 9 m (30') and larger.B Single 2650 2600 3215 Position blocks so line pulls down and out to keep the sail flat and prevent C Mastbase block 222 1986 1988 lateral loads on the luff rope or luff sliders.D Bullseye 339 237 237Lazy JacksA Lazy Jack kit 252 253 254A ALazy Jacks: Lazy Jacks contain mainsails during reefing and dousing. They work exceptionally well with full-battened mains, but are also used with conventional sails.268"