Hard drive “defense system”

I’m looking at hard drive specifications, and I noticed that the 160GB Seagate hard drive has the following features: “350 Gs non-op shock, 3D Defense System”. I assume 350 G’s means that if you drop it out of an airplane (or at least off a desk) it will still work, as long as it’s not in operation at the time, which is quite cool. But what does a “3D Defense System” on a hard drive do, and will it result in accidents like this?