Milspec’s Pro Lock Extension Cord with locking u-ground (straight lade) connectors, and the traditional Twistlock cords with L5-20 plugs and connectors, prevents extension cords from being accidentally disconnected and resulting in a loss of power. To release, pull down on the connector collar to disconnect the cords. The built-in continuous ground monitoring system indicates ground continuity. The 12-gauge cord comes in blue or green and 25- and 50-ft. lengths.