Each of our Pro Lock Extension Cords are molded with our patented Pro Lock connector.  When a cord with a standard u-ground 15A-125V, plug is inserted into our Pro Lock connector, it locks and won't pull apart.  This prevents accidental disconnects that result in an inconvenient loss of power.  To release, simply pull down on the connector collar to disconnect the cords.  We have added our patented "CGM" Continuous Ground Monitoring system to our Pro Lock connector that indicates there's ground continuity in the cord for added safety.