The metal legs, which are designed to stack several racks together, are detachable, allowing me to use only the plastic slatted base. It's about 4 centimeters tall, which is enough elevation to allow air to flow underneath the computer to prevent it from overheating.
The metal legs are still useful though, I often reattach them when I'm using my laptop in bed, and it works like a small breakfast table for me to stick my legs underneath.
Seriously, don't spend a lot of money on a laptop stand. Save yourself a few bucks and just pop into your nearest stationary store or household storage accessory store and pick up anything reasonably priced that will work.