Perfume Studio Set of High Quality Roll On Aromatherapy Bottles 10 ML / .33 OZ. faint purple glass Rollers with stainless steel ball for a smooth and easy application and Silver Caps. "A steel Roller Ball works better than plastic for applying essential oils to your skin." These Roller Bottles are ideal for Essential Oils, Aromatherapy, Home Made Lip Gloss, Perfumes, Colognes, and More.The Absolute Best Quality Roller Bottles For an Optimum Skin Application! Long Lasting and Refillable. Perfect Size For Travel; 1/3 Oz. NOTE: Please make sure you don't fill roller bottles past the lower part of the neck to prevent leakage or metal ball from popping out. DO NOT USE WITH FRACTIONATED COCONUT OILS OR OTHER SIMILAR HIGH LUBRICANTS. THESE TYPES OF LUBRICANT OILS WILL FORCE THE METAL BALL TO POP OUT.