Swiss M.71-79 Helmet With Backpack Attachment.

The M1971 helmet  is a military steel combat helmet used by Switzerland.

The shell of a near hemispherical shape with prominent flares on both sides and stamped in 1.15mm steel. It includes four rivets where the liner attaches to the shell, which is painted matte dark olive green with a textured finish. Towards the rear, two vent holes are present to increase airflow and comfort.
With hook to attach the helmet to a backpack.

The liner itself consists of a metal band running the inside circumference with a foam spacer between it and the shell. Attached to the band are four leather pads, attached to the rear of these is a leather pouch where simple pieces of thick felt are used for sizing to one's head. A drawstring connects all four pads for further sizing. The chin strap is a four-point setup with the straps attaching to the shell in the same place the liner itself does, both straps connecting with a simple hook and catch system.