What is a key characteristic of safety helmets for high-impact activities?

A key characteristic of safety helmets designed for high-impact activities is that they have a rigid outer shell. This feature is essential because the outer shell is designed to absorb and dissipate the energy from impacts, protecting the wearer’s head from injuries. The rigidity of the shell helps ensure that it does not easily deform or shatter upon impact, thereby providing maximum protection during high-risk activities such as construction, industrial work, or sports.

While lightweight materials can enhance comfort and flexibility, and additional padding may improve fit and comfort, the primary function of the helmet's design is to provide hard protection against high-impact forces. Bright colors can enhance visibility and safety in certain environments, but they do not contribute directly to the helmet's capacity to protect against impacts. Thus, it's the rigid outer shell that plays the critical role in ensuring safety in high-impact scenarios.