Forbes says B A S U is a great gift for Travelers

That little can of pepper spray may repel everything from late-night muggers to bears in the forest, but not if you spray it in the wrong direction or want to carry it on board a flight. The [eAlarm], about the size of an electronic key fob, lets you pull a plug for a piercing 120 decibel noise bomb to shock and repel the attackers (120db is up there with a jackhammer, thunderclap or loud rock concert). When the danger's over, re-insert the plug to use it again. The newer, more rugged [eAlarm+] is meant for outdoor use, with a 130db blast. Downside: the sound can be equally unpleasant (if less of a surprise) for you, and prolonged use can contribute to hearing loss. Here's hoping you never need to use it. 
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Full article: http://www.forbes.com/sites/andrewbender/2016/12/13/10-great-gifts-for-travelers-2016-edition/#44502bb614d0