Move the sliders back and forth in this unique sound book to hear the building site come to life. Move the sliders back and forth in this unique sound book to hear the building site come to life. From noisy diggers and clanking cranes to forklift trucks and road-rollers, the charmingly illustrated scenes are full of busy vehicles. Each slider has two different sounds on it - move it one way to see and hear one vehicle, then move it back again to hear a different one.