The B366B is a 2 oz black HDPE plastic diamond round bottle with 20-410 neck finish. The diamond round, also called a diamond round and plastique round, is a cross between the boston round and the cosmo/bullet/imperial round. It is usually tall and slender like the cosmo/bullet/imperial round, but the rounded shoulders are more like the boston round. High density polyethylene (HDPE) is marked with the resin identification code of 2. HDPE has a high tensile strength, good resistance to chemicals, good impact resistance, highly rigid, and highly scratch resistant. This item has a 20-410 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.