The B213NT is a 1/2 oz natural-colored LDPE plastic boston round bottle with 15-415 neck finish. The boston round bottle is distinctive in its classic shape. Characteristic of the boston round are its rounded shoulders and rounded base. Low density polyethylene (LDPE) is marked with the resin identification code of 4. LDPE has high tensile strength and low density. This makes it very tough and "squeezable." LDPE has medium clarity, good chemical resistance, high impact resistance, and high scratch resistance. This item has a 15-415 neck finish. The first number refers to the diameter (in mm), and the second refers to the closure depth, style and thread. This container can be paired with a closure with a matching finish. Natural-colored containers are not actually colored. This is the natural color of the plastic, which is a milky translucent color. This translucent color shows product level, or how full (or, if you're a pessimist, how empty) the container is.