This is the Cuisinart food processor DLC-7 stem that attaches to the discs that are used to slice and grate. It is compatible with the DLC7 Cuisinart food processor. It has a sliding mechanism that is pulled back to attach to the interchangeable discs.
If you are replacing parts for older Cuisinart machines, you may have had discs that each had their own stems. Cuisinart no longer manufactures the discs and stems attached. You must now purchase those two parts separately.