Dropper Cap Assembly for our 1oz Amber Bottles is ideal for measuring out small amounts of liquids, in applying oils, and creating blends. Whether you are making your own tinctures, custom fragrances or essential oil blends or using them in a lab setting, these quickly become indispensable! Construction: a glass tube with black polypropylene closure and rubber squeeze bulb. TIP: To extend the life of the rubber bulb, we recommend that you store the bottles upright, and that you replace the dropper cap with the 20/400 phenolic polycone cap for travel, shipping or extended storage. Scroll down to the From the Blog section to learn more about our Amber Bottles, Lids & Droppers.