2 ml Purple Glass Vials with Metal Roll-ons and Black Caps (Pack of 144)Economical way to share diluted samples of single oils and blends or your own mixtures. Save big by buying in bulk! Ideal size to introduce oils. Durable metal rollers for smooth flow. Best with 1: 1 ratio of essential and carrier oils. Handy for travel too. Details Tiny sample vials are a handy way to share and apply essential oils blends and massage oilssimply roll on the skin as needed! The color helps protect oils from damaging ultraviolet light.