30ml Cobalt Blue Glass Boston Round Glass Dropper Bottles, with new Metallic Overshell Collar, Glass Bulb Pipette Medicine Droppers. Perfect for protecting and storing your valuable Essential Oils, Carrier Oils, Argan Oil, Beard Oil, Medicines, Serums, etc. these bottles are refillable too . These are the perfect solution to precision distribution of your products, drop by drop, and for measuring out essential oils drop by drop to combine into fabulous perfumes and blends! All of these glass bottles are UV resistant, to keep your oils fresh and stop degradation from harmful light. Well Made Glass Construction.