I don't see the term lock buckle in any description of your case, but the only thing I can think of is that it somehow refers to the way that the drive bays rotate out on a hinge for easier insertion/removal. Looking closely at several pictures of your case on newegg that is the only thing that sticks out to me as unique about the case.
That's kind of a cool feature. My htpc case is a hassle to work get things in and out of.
I wouldn't even use the 275W power supply that comes with it though.