Without a helmet, the HANS would have to bolt to your skull.Legion81 wrote: I thought something similar to the HANS device .
A mountain lion attack is generally over as soon as it's begun. To "react" to a big cat on your back, locking jaws on/around your head and neck, you'd need a presence of mind that the vast majority of us just.don't.have.
But, I have put some thought into being attacked over the years. You're best hope would be to have a simple sharp object in your hand... at all times. Like an ice pick, not a blade, just something sharp and strong, and at least 12" long. You aught to be able to inflict enough pain/damage with it to get the cat off of you... for a second at least. In the panic of the moment, you're probably just as likely to stab yourself.
A prevention option may be a simple scarf impregnated with something that tastes awful, yet doesn't irritate the skin. Good luck with that one.
Just don't hike alone, all party members should have a knife of some kind. Or, hike with an ornery mule.