35mm Plastic White Film Canister with Lids, Pack of 50. Perfect for Alka-Setzer Rockets, Geocaching Containers MULTIPLE USES - Very popular for science class experiments, geocaching containers, first aid kits and storage of small objects. MICRO PRECISION FITTING LIDS - Its airtight design make it perfect for building pressure inside, making it perfect for Alka-Seltzer Film Canister Rockets INCLUDES 50 35MM WHITE FILM CANISTERS WITH CAPS - All film canisters are empty,new and made of plastic.