TheseOne Hole Rubber Stoppers are shaped to work with most types of labware. They come in a variety of sizes ranging from #00 to #13. Each package weighs approximately 1 lb. Stoppers are designed for a long working life.
The stoppers are made with high-grade, pure gum rubber. They are formulated with low sulfur content. Sizes are notated on the top of each stopper. They are recommended for users age 7+.