This is a 9 foot long replacement power cord for DeWalt polishers like the DWP849 that we sell.  It is rated to 600V so nice quality that will last for years. 

We recommend replacing the strain relief at the same time.  We also recommend replacing carbon motor brushes and blowing out the dirt.  Your old tool will be like new again.

You'll need to take the back half of the yellow case apart using T20 drivers. You'll also need a soldering iron and a T15 bit too.  It's pretty easy if you take your time.