What is a key requirement for ice hockey helmets to ensure safety?

A key requirement for ice hockey helmets to ensure safety is that they must withstand high-velocity impacts and high-mass-low-velocity forces. Ice hockey is a contact sport where players are frequently exposed to fast-moving objects, such as pucks, and collisions with other players. Helmets must be designed to absorb and dissipate these forces effectively to reduce the risk of head injuries. The ability to withstand both the high-speed impacts from flying pucks and the lower-speed, higher-mass impacts from collisions is critical for protecting the player's head.

While other features like being lightweight and flexible can contribute to comfort and performance, they do not address the primary safety concern that high-velocity and varying types of impact present. Similarly, although a decorative design might be appealing for aesthetic reasons, it does not contribute to the safety features necessary in a helmet. Lastly, a helmet that fits all head sizes without adjustment may not provide the optimal level of protection, as a proper fit is essential for ensuring that the helmet stays in place during impacts. Therefore, the focus on impact resistance is paramount in the design and regulation of ice hockey helmets.