These power cords receive special approval from UL which is based on high quality construction and peak performance. The Green Dot marking on the face of the plug indicates the cord has been tested and is ready for use in a hospital environment. Heavy Duty Hospital Grade cords use plugs and connectors with high amperage and/or voltage rating with cable of a large gauge. These cords can be used to safely power medical devices that draw lots of electricity. The Auto-Lock C19 is an internal mechanism that holds the pins of the C20 Plug or Inlet to keep your device from being accidentally unplugged! These components are sturdy yet unplug with ease whenever you want to remove the power cord!