The products come in an array of sizes: 2.5, 3, 3.5, 5, 7, 9, 12, 15, 20, 25, 40 and 50 Dram. With this many sizes, one can be confident to find the best-fitting snap cap vial. They can be used for storing, shipping and securing anything that will fit inside. They come with a snap-on cap keeping everything safe.