XT60U-M :  High-amp secure battery connector for R/C. Upgraded version of the XT60 connector. For this new XT60U series, the "-M" means male; this connector is typically on the motor, the Charger, the receiver, or the switch harness.  Used for R/C hobby Receiver and Motor applications. This XT60U connector will accommodate the semi-circular XT60U-F connector.