A push-pull locking system gives the VISE-LOCK metal circular connectors an exact and reliable connection, even in rugged environmental conditions. The plug has fingers that latch into a groove inside the receptacle. An easy pull on the cable causes the latching fingers to lock tighter, making connector separation virtually impossible. Disconnection requires users to pull slightly on the outside housing of the plug, which causes the latching fingers to release from the receptacle.The compact locking mechanism allows for connector sizes as small as 0.394” (10 mm) outside diameter (size 0) to be used. Sizes range from 8 mm to 18 mm. The connectors are available in up to 27 positions and in four sizes, which come in three series: Series S has hermaphroditic insulation bodies for easy blind mating; Series B has keying between pin and groove; and Series F uses internal half-shells as alignment guides.