Theses stickers are acid-free and adhere to virtually any surface. Crystal Elements offers a wide variety of clear stones in various sizes including 2mm, 3mm, and 5mm. The assortment stones include sizes 3mm, 4mm, 5mm and 6mm. These stickers also are available in a variety of shapes, words, designs, alphabets and fashionable colors. Size, color, shape and number of stickers varies by package.