Perfume Studio Metal Ball Roller Bottles for Essential Oils - Cobalt Glass 5ml - 7ml Capacity (9) Practical 5-7 ml Clear Glass Roller Bottles with Metal Balls and Black Caps (9 Bottles) Durable and Easy to Use Roll Ons NOTE: Only use these Metal Ball Rollers with pure uncut oils. Do Not use Metal Ball Rollers with diluted or carrier oils, particularly fractionated coconut oils. This is a high lubricant oil that will force your metal ball to pop out. For these type of oils you should use plastic ball roller bottles. Use with your 100% Pure Essential and Grade-A Perfume Oils Refillable and Reusable Roll On Bottles