Usually, the shell of the helmet is made of high-strength materials, such as metal, engineering plastics, Kevlar fiber, etc., through its deformation to absorb most of the impact; the lining material has the ability to absorb sweat, keep warm, and absorb shock. Military helmets often have the functi

You are packing for your first outdoor climbing trip. You have the harness, the shoes, and the chalk bag. Then you realize you don't have a helmet. You glance over at your bicycle helmet sitting on the shelf or the construction hard hat in your garage. "A helmet is a helmet, right?" you might ask yourself.

Gravity is the constant companion of every climber. Whether you are scaling a multi-pitch trade route in Yosemite or projecting a sport route at your local crag, the risk of falling rock or an awkward swing into the wall is always present. While we often obsess over the rubber on our shoes or the rating of our carabiners, the helmet is arguably the most critical piece of safety equipment in your pack.

You have packed your rope, organized your quickdraws, and stuffed your harness into the bottom of your bag. But as you zip up your pack, you realize there is one awkward, bulky item left: your helmet. It takes up too much crucial volume to go inside, yet it feels precarious dangling loosely from the outside.