These high quality, Cobalt Blue Glass Roll-on bottles with stainless steel roller balls are perfect for use with essential oils, perfume oils, and other liquids. Snap in the roller-ball by gently placing the roller-ball in the bottle and then firmly tighten the cap until the roller-ball snaps in. Use the roll-on bottle to apply the perfect amount of product each time. Remove the roller-ball by applying pressure with the cap. The beautiful, Cobalt Blue glass provides protection from potentially harmful light and the convenient size makes it perfect for travel.