United Scientific Rubber Stoppers, 1-Hole, #7 Sizing, 1 lb

United Scientific 1-Hole Rubber Stoppers in #7 sizing are essential laboratory consumables designed for secure sealing of flasks, test tubes, and other glassware requiring tubing or thermometer insertion. These premium natural rubber stoppers provide an airtight seal while allowing passage of glass tubing, thermometers, or other instruments through the center hole, making them ideal for distillation setups, fermentation experiments, gas collection, and general chemistry applications.

• Size #7 with single pre-drilled center hole for tubing or thermometer insertion
• Constructed from high-quality natural rubber for excellent flexibility and chemical resistance
• Top diameter: approximately 31mm; Bottom diameter: approximately 25mm
• Sold by weight: 1 lb package provides multiple stoppers for laboratory use
• Suitable for use with compatible flasks, test tubes, and laboratory glassware
• SKU: RST7-H