Parts of a safety helmet: shell, harness, headband, strap

Post · 3 October 2026 · Figures reviewed 6 October 2026

A safety helmet looks like one piece, but it works as a system: a hard shell, and inside it a harness that holds the shell off the head. Each part has a job, and knowing them makes a helmet easier to fit, check and keep.

The shell

The outer shell spreads the force of a falling object over a wider area and turns aside sharp ones. MM lists the CH01 and CH02 shells in HDPE / ABS, in seven colours, with or without ventilation holes. The front peak keeps sun and rain off the face.

The suspension harness

Inside, a cradle of straps holds the shell clear of the head. That gap matters: when something strikes the shell, the harness stretches and the shell moves before the blow reaches the skull, which is how IS 2925’s shock test limits the force reaching the head. MM lists a 6-point suspension with a cushion pad.

The headband

The headband sets the fit, for head sizes 53 to 63 cm in MM’s listing, and adjusts by a push-and-pull ratchet or a 6-hole nape band. Ratchet or nape explains how each one is set.

Sweatband and chin strap

A sweatband keeps sweat out of the eyes and the harness clean; MM lists a replaceable absorbent terry towelling sweatband as an option. A chin strap keeps the helmet on when the wearer bends, climbs or works in wind; MM’s is adjustable, in soft-weave terylene webbing.

Accessories

MM also lists a helmet with a lamp, for work in the dark. Whatever is added, it should not mean drilling or cutting the shell, which weakens it.

Checking the parts

• Shell: no cracks, dents or chalky, faded patches.
• Harness: every strap and clip intact and clipped in; no stretched or torn webbing.
• Headband: the ratchet holds its setting, or the nape band stays where it is set.
• Chin strap: buckle closes and releases, webbing not frayed.

The tests behind the ISI mark: IS 2925 safety helmets.