Our high-quality rubber stoppers are soft, non-greasy and have a durometer of 45. They are sold in a one-pound pack. These stoppers are size 12 and are drilled with one hole. Size 12 stoppers have top diameter of 64mm, a height of 25mm, and a bottom diameter of 54mm. Approximately 5 size 12 stoppers are included per one-pound pack. Great for various lab uses Size 12, 1-Hole Comes in a 1lb bag Our high-quality rubber stoppers are soft, non-greasy and have a durometer of 45. They are sold in a one-pound pack. These stoppers are size 12 and are drilled with one hole. Size 12 stoppers have top diameter of 64mm, a height of 25mm, and a bottom diameter of 54mm. Approximately 5 size 12 stoppers are included per one-pound pack.