So, we don't actually recommend this for keeping away bears. The most dangerous thing you're likely to encounter are other humans trying to break into your shelter or threatening you when you evacuate. This spray shoots 30 feet and lays a thick pepper-based fog. If it send a grizzly scurrying away, imagine the reaction to an antagonsitic person. And it's non-lethal.
Frontiersman Bear Spray
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Bottom line: A non-lethal defense method — against people who might be threatening you (or yes, even bears, though that's actually less likely).
Recommended for: Home Shelter, Go-bag.
No. of units recommended: At least two with every party or longterm shelter.
Be aware: Pepper sprays are illegal in some places, including New York City.
We've tested this in an open field, and were amazed just how far it shoots. But you don't want to be in an enclosed space, clearly, and the wind can shift and affect you, as well. Still, this will shut down an aggressor VERY quickly.