Tesla Gold Series Portable comes in a white ABS case featuring a rechargeable 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 Blushield home 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 is designed for short outings or travel between protected zones in order to keep one balanced and protected without experiencing the contrast associated with 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. When working out or you are in areas where moisture may be present, a plastic baggie may be used to protect the internal components of the Portable. The warranty does not cover water damage or damaged power buttons from being dropped. 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 Plugin model or the Tesla Gold Series Cube model would be great to use in tandem with the Portable. Use the Tesla Gold Series Auto in your car or SUV.