Roller-ball roll-ons are small 10 ml glass bottles, about the size of a lip balm. Designed for dermal use, roll them on pulse points such as inner wrists, forearms, and neck areas. The essential oil molecules are thereby inhaled and absorbed. They travel well and fit neatly and securely into your purse, gym bag, glove-compartment, back-pack, or desk drawer. Caps are tight to prevent leaks. The roller-ball itself is stainless steel, and because of this, may have to be rolled a few times on your skin to initially work. Petal Potion products contain only 2 ingredients: high quality fractionated coconut oil and pure essential oils. The essential oils are obtained only from suppliers who use strict quality control measures to ensure reliable high quality oils.