Slider Sound Books Moo!In this unique sound book, move the sliders back and forth to see and hear the farm animals come to life. Move each slider and you'll see a farm animal and hear the sound it makes but that's not all! Move the same slider back again and you'll see and hear a different animal. Children will love discovering all the surprises hiding in the sliders as the cows, pigs, sheep, and hens get noisy on the farm.