Discovery Channel Super Sounds View-Master Dinosaurs - 3 Reel Set by 3Dstereo To hear sound you need the Super Sound FX Talking View-Mater Viewer - will work in any View-Master viewer but silently The Dinosaurs Super Sound Talking View-Master Reel Set contains 21 Mesozoic packed 3D images There are three reels plus a handy storage case which doubles for a Sound Cartridge that you slip into your Super Sound FX Talking Viewer to get exciting realistic and clear Sound FX, Music, and Character Voices