The design of the weapon, including the quillon (crossguard) shape, blade profile and blade length, are specific to each style of martial arts, the precise lineage, and individual. For example, some martial arts lineages flip the butterfly swords between the forward and reverse grip like a Sai, and consequently need a quillon that will fit the hand during a reverse grip. Some lineages trap the opponent's staff or blade between the quillon and spine, and they need a longer quillon closer and more parallel to the spine than would fit a hand after flipping. Some schools like a hybrid quillon design that is adequate for both flipping and trapping, but optimal for neither.