"A hard hat is a type of helmet predominantly used in workplace environments such as industrial or construction sites to protect the head from injury due ...
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to falling objects, impact with other objects, debris, rain, and electric shock. Suspension bands inside the helmet spread the helmet´s weight and the force of any impact over the top of the head. A suspension also provides space of approximately 30 mm (1.2 inches) between the helmet´s shell and the wearer´s head, so that if an object strikes the shell, the impact is less likely to be transmitted directly to the skull. Some helmet shells have a mid-line reinforcement ridge to improve impact resistance. The rock climbing helmet fulfills a very similar role in a different context and has a very similar design." - (en.wikipedia.org 30.11.2019)