These are Lava Stone necklaces. The main lava stone is 8mm in size. There's another lava stone to clamp the necklace together. You can choose between two black or brown materials either in matte waxed cotton or genuine leather. You can also adjust it to three different lengths that you feel most comfortable using. 🌼Lava Stones are used to diffuse any of your favorite essential oils just by rubbing some on it! ✌ ✔Price is firm, will not accept lower offers! ✔10% off 2 or more!