The Parkit360's Transformer 15K-BF Ball Mount Battery Powered Trailer Dolly is great for simple yet precise parking. Just engage the motor, connect the battery, secure the Ball Mount, and go! Arrives ready to go, right out of the box with a pre-installed (2) 12V U1 Battery and Charger, 6.5” Wide Tires, and 7-pin Trailer Brake Plug for safe, convenient parking.