There is a lever on it with reasonable safety. You have to lift up (against a spring) and turn. i.e. it wont gradually open with vibration, etc. Having one, I dont feel like it something that would be opened unless you intended it to.

There is also an option for a safety clip, its like a spring-ring. I personally think its overkill.

Here's some reading if you're interested http://www.fumotousa.com/faq.htm

If its not for you, thats cool too - just passingon the info.