 Roller furling is typically used for foresails such as jibs or genoas.A mainsail may also be furled by a similar system, whereby the sail is furled within the mast or around a rotating boom (or around a rotating shaft within a boom).Although staysail roller-furling is effective and very common, inmast or in-boom mainsail furling involves some compromises, and mainsail slab reefing gives a better sail shape.