16th century close-helm
The close-helm style changed little from country to country in the late16th century. The close helm was an ideal helmet for Knightly sport and combat. It encases the entire head fitting closely and terminating with an attached series of lames, called a gorget, to protect the neck. The visor and the upper bevor (plate with the ventilation holes) can open individually to allow selectively more air in when not in harms way.
Below is not a close helm but rather it's predecessor known as an armet. I based this Helm on one belonging to King Charles V of Spain. This is one of my ongoing side projects. Someday I will get around to etching the visor and doing the final assembly.