Z Series Improved DC Power Plugs Switchcraft Z Series Improved DC Power Plugs take the proven design of the original power plugs and improve on it to make it safer and more versatile. These power plugs are engineered for a wide variety of critical applications. The touch-proof / scoop-proof construction provides added safety, while grooves improve retention. The larger cable clamp accommodates cables up to 5.3mm (0.210') and improves strain relief. Switchcraft Z Series Improved DC Power Plugs are available in various sizes and compatible with standard DC power jacks.