The enclosed helmet provided full protection for the head and deeper protection for the sides than previously available in helmets of the era. The helmet featured slots for the eyes and for breathing.
The helmet was created by adding a face protecting plate and extending the sides of a flat topped helmet such as a nasal helm, and thus creating a more cylindrical helmet.
The helm would have been worn over a mail coif with additional padding around the head to help absorb the force of blows against the helmet.
The helmet was only used of men of Knightly rank, with many Knights still preferring to wear nasal helms. Due to the restrictions to sight and sound that the enclosed helmet imposed.