Check the listing for details. Solid Rubber Stoppers 4x8x20mm, 12 Pcs Tapered Lab Seal Rubber Stopper Black. Condition: New. Listed at 14.89 USD. Solid rubber stoppers are commonly used in laboratories, households and industries to seal or block openings such as test tubes, beakers, bottles, water pipes, drains. They are also widely used for protecting key components during processes like spraying, electrophoresis, electroplating, anodization, sandblasting, and shot blasting.SpecificationColor: BlackMaterial: RubberMax Diameter: 8mm / 0.31 inchMin Diameter: 4mm / 0.16 inchHeight: 20mm / 0.79 inchPacking List: 12Pcs x Solid Rubber StoppersAdvantageThe lab plug is made of solid rubber material with high temperature resistance, acid and alkali resistance, corrosion resistance, along with good sealing performance. It is sturdy and durable, not easily deformed, washable, and can be used for a long time.