Nut

Buffer hex hat nut.  This tool is a replacement for the nut that attaches the rubber backing pad to a buffer (notably the DeWalt buffer).

But, frankly speaking, why not buy a velcro backing pad instead (see "Backing Plate, Rotary 7" Velcro Backing Plate" under "Buffing Pads and Supplies") and forget the nut.  It will not only end the hassle of removing the backing plate when mounting pads but it will allow you to choose from a much larger selection of available pads.  

Item #363

$5.95 USD