The visor could be hinged or a completely separate piece that attaches with a strap. Also the person wearing this would likely have assistance getting suited up.
This particular type of helmet is a 16th century "Armet" which is a style of closed helm. There are typically 2 types of closed helms, one is actually just called a "closed helm. "
An armet has cheek plates that close around your head to form the bevor (bit that protects your chin and neck to fully protect your head.
A "Close helm" has a single hinge point that the visor and bevor hinge on to close onto your face.