Ryobi Battery Adapter to run on Milwaukee M18 or Dewalt 18V Battery – Battery Adapters
DM18RL Adapter Converter, Battery Adapter for Dewalt for Milwaukee M18 18V/20V Lithium ion Batteries Convert to for Ryobi P108 18V Li-ion NI-CD NI-MH ABP1801 Battery, with USB Port - - Amazon.com
Badaptor Milwaukee Battery Adapter to Ryobi 18v One+ Works with Ryobi – Knottec Wood Repair Glue