The Celestron Car Battery Adapter (For all NexStar Models) allows you to power your telescope from your car. This is a handy accessory for astronomers that like to star watch in isolated areas to avoid light pollution. This adapter attaches your telescope to a 12V battery pack or your car s cigarette lighter. The cord is 25-feet long that gives you a great deal of reach between your telescope and the power source. With the Celestron Car Battery Adapter you have everything you need to take your stargazing adventure anywhere you like. The barrel connector can be used with any telescope that uses a receptacle with an outside diameter of 5.5mm and an inner diameter of 2.1mm and a tip positive polarity.