Tesla Gold Series Portable comes in a full alloy case featuring a rechargable battery. This can be recharged using the USB cable provided, at any computer or USB adapter charger.
This portable model is for use outside your plugin protected area and is not intended for use inside your home or office as a substitute for the plugin or larger models as it does not offer the same level of protection.
The portable model is designed for short outings or travel between protected zones in order to keep one balanced and protected without experiencing the contrast associated from going from one protected zone to another.
The Portable is not water resistant and needs to be in your pocket or purse and used between protected zones not as a stand alone protection device.
Tesla Gold Series Portable is great for people who travel a lot in electric trains or who drive electric vehicles. For protecting a large area the Tesla Gold Series Plug-in model or the Tesla Gold Series Cube model would be better.