DC Power Jack Female Socket Barrel Connector - Panel Mount - 5.5 x 2.1mm. Socket: 5.5mmx2.1mm Mounting Hole: 11mm/0.43" Includes insertion switch: 3rd pin is normally closed to pin 2, but upon insertion of a plug, pins 2 & 3 are disconnected. Useful for cutting power while charging or switching from batteries to external power. PINS: 1: Center Pin 2: Outer Connection 3: Switch (NC to 2, disconnect upon insertion)
eBay