Apple Mac Pro Feet Kit
 
Use the Mac Pro Feet Kit to install stainless steel feet to the bottom of your Mac Pro. The standard Mac Pro comes with four feet already installed, but if you purchased a Mac Pro with wheels, you can replace each of them with feet for improved stability.
Installation required. A 1/4-inch to 4 mm hex bit is included, but additional tools are necessary. Replacing the Mac Pro wheels with feet reduces approximately one inch to the height of the frame.