Rubber Stoppers (Rubber Bungs) – 2 Hole, 21mm Bottom (Pack of 10)

These 2‑hole rubber stoppers, also known as rubber bungs, are durable and versatile laboratory components designed to securely seal glassware while allowing two separate connections through the stopper. Supplied in a convenient pack of 10, they are ideal for routine use in school, college, and teaching laboratories.

Each stopper has a 21mm bottom diameter, 24mm top diameter, and a 28mm length, providing a reliable fit for a range of flasks and reaction vessels. The two pre‑drilled holes allow for the insertion of tubing, thermometers, sensors, or delivery tubes, making these bungs well suited to more advanced experimental setups.

Manufactured from high‑quality, flexible rubber, these stoppers offer an effective airtight seal while remaining easy to insert and remove without damaging glassware, supporting repeated classroom use.

Key Features

• 2‑hole rubber stoppers for laboratory applications
• Bottom diameter: 21mm
• Top diameter: 24mm
• Length: 28mm
• Supplied in a pack of 10
• Allows two tubing, probe, or thermometer connections
• Flexible rubber construction for a secure, reliable seal

Ideal for School Science Lessons & Practical Experiments

These 21mm 2‑hole rubber bungs are ideal for use across KS3, GCSE, and A‑Level science, supporting practical investigations that require sealed apparatus with multiple connections.

• Connecting gas delivery and pressure‑release tubing
• Allowing simultaneous use of a thermometer and delivery tube
• Supporting gas generation and collection experiments
• Constructing more advanced chemistry reaction apparatus
• Enabling safe, repeatable student practical investigations

Reliable, reusable, and easy to handle, these 2‑hole rubber stoppers are an essential laboratory consumable that helps teachers and technicians deliver safe, effective, and well‑structured science lessons.