The style is sometimes referred to as a 'crusader helmet', but also as a 'pot helm', and a later variant with a more conical top is known as a 'sugarloaf helm'. In Spanish they are called yelmo de Zaragoza, referring to Zaragoza where they were introduced for the first time in the Iberian peninsula.
Although the great helm offered greater protection than previous helmets, such as the nasal helm and spangenhelm, it limited the wearer's vision to some extent, and provided poor ventilation. A knight might wear the close-fitting steel skull cap known as a cervelliere, or its later development the bascinet beneath the great helm. A great helm may have also an attached mail collar, or camail, to protect the wearer's neck, throat, and shoulders.