Vroom!Move the sliders back and forth to hear the different vehicles zooming along in this unique and exciting sound book. Move the sliders back and forth to hear the different vehicles zooming along in this unique and exciting sound book. When you move a slider one way you'll see and hear one vehicle and when you move it back the other way you'll see and hear another one. There are planes, trains, cars, motorbikes and buses to discover, all driven by Ailie