This stem attaches your slicing and grating disks to the motor of your food processor. Older model slicing and grating discs had their own attached stem, but newer model parts require this detachable piece. The fact that the disc detaches from the stem makes storage easier, and it allows you to purchase multiple interchangeable discs that all work with the same stem. It works via a sliding mechanism that is pulled back in order to attach and detach each disc.
Note: This stem is compatible with the DLC-7 processor. Cuisinart no longer manufactures discs with attached stems. If you need a replacement, you must purchase each piece separately.