Taking it's name from the large conical lumps created during the sugar refining process, the "sugar loaf", this great helm came into being during the late 13th Century toward the end of the Crusades, meaning that it saw some, but limited, use by crusading knights. 

The conical top of the sugarloaf style helmet helps to deflect overhead blows and has a stronger structural design than the classic flat-topped great helm. That being said, even with the addition of ventilation holes, this helmet was heavy, hot, and didn't allow for great air circulation, making them uncomfortable for protracted use, which meant that many knights wore a secondary cap or helmet underneath to allow them to remove the helmet during battle for a breather, while still remaining relatively safe. 

This particular sugarloaf helmet is made from 16 gauge steel and has an adjustable liner to help it fit to the appropriate sitting height for the wearer.