A helmet can make a blow to your head that would otherwise be harmless MUCH more comfortable to endure. If only because it will probably prevent scalp laceration and/or bruising. If the blow is serious enough to kill or seriously damage your brain then a helmet cannot save you. Do not spend more than $80 for a helmet, ever. There is nothing that a $300 helmet can do that the $80 (or $30) can't. Styrofoam is the active ingredient in all helmets and the ONLY way (as outlined above) to make a 1.5" thick liner twice as effective is to make the liner 3" thick! Would that be practical? Helmets keep us safe because most of us don't ride enough to run up against the law of averages of serious helmet failure. With all due respect to the o.p. I don't think I have ever read a more pointless exercise in mansplaining. WTF? I have NEVER seen anyone supply an explanation about how helmets work that was incorrect or correct for that matter. The intuitive deduction is that the material of the helmet liner absorbs the blow. Somehow. No one cares how. This is America. How many people could correctly explain how a lightbulb works. The old kind before LED's. Again, WTF? My admittedly harsh reaction comes mainly from the unsolicited nature of the o.p. I'm not understanding why we needed this.