This is an inverter cable for the 13" Macbook. There are two types of connectors on the inverter cable. The earlier models used the 4-wall connector with a typical socket type end and the later models used the 3-wall connector that snap in. You can see the difference from the images below. Some extremely early revisions of the Core 2 Duo machines did come with 4-wall style connectors. Be sure to check what you have before ordering.
Core Duo (4-wall)Core 2 Duo (3-wall)