I've just purchased a few simple hardware rackmount devices, and a rack case. I've never set anything like this up before. I've been told that the devices' faceplates are screwed to the rack, and no other support is required.

Is this true? Are rack devices only attached by the faceplates, and there's no other support? Some of these devices are kind of heavy and it doesn't seem like enough support to handle the weight, particularly during transport where they bump around. 

I want to make sure I'm not missing something.