4 ounce glass frosted boston round bottle with 22-400 neck finish. Boston round bottles have the distinct rounded shoulders design that makes it popular in many industries. Glass is a great option for products that do not fit with plastic containers for packaging reasons. These boston rounds are available in cobalt blue, amber, frosted, clear and white colors. Smaller boston round bottles are available as droppers that include child-resistant dropper caps. Perfetc. for essential oils and other personal care products. Remember to test your product with the specific container to assure the corretc. fit and compatibility.