Fisher-Price Peek-a-Boo Stack 'n Surprise Blocks Choo-Choo Peek-A-Boo Choo Choo Bring building fun to a new level with music, lights, and peek-a-boo, pop-up action! Press the smokestack for music, sounds and light-up fun Train comes to life as baby pushes it along Bright colors, smiling faces & pop-up action offer visual stimulation