Amazon.com: Echoyee for Dewalt & for Milwaukee to Ryobi Battery Adapter, Fit for Dewalt 18v-20v & for Milwaukee 18v M18 Lithium Batteries, DM18RL Converter use for Ryobi 18v ONE+ Cordless Power Tools :
New Battery Adapter Portable for Milwaukee Converter to RYOBI 18V Cordless Plug Tools - Walmart.com