Amazon.com: JJXNDO for Dewalt 20V to 18V Battery Adapter, 2-Pack DM18D Upgraded Version DCA1820 Converter for Dewalt 18V/20V & for Milwaukee M18 18V Battery to Work for Dewalt 18V Nicad & NiMh
DeWalt's 18v Battery Fits Old and New Tools - FineWoodworking