This is a robust solar powered car. A fun & efficient way to teach and demonstrate how the solar energy and cells work. The solar car can run entirely on solar power, or by flicking a switch, run on internal batteries (which can also be charged by the solar cell). The built-in battery compartment will accept a rechargeable 'AA' battery. The unit also has a pair of terminals from which a current of 2v dc can be drawn. Overall size is 5 inch(140mm) L x 2.75inch (70mm) W x 3inch (75mm) H. Rechargeable battery shown, but not included.