Rubber Stoppers / Rubber Bungs – 1 Hole, 21mm (Pack of 10) [1189]

These high‑quality 1‑Hole Rubber Stoppers are designed to provide a secure and airtight seal for a variety of laboratory glassware used in school science experiments. With a 21mm bottom diameter, 24mm top diameter, and a length of 28mm, they offer a snug fit for medium‑sized test tubes, flasks, and vessels.

Each stopper features a single pre‑drilled hole, making it suitable for glass or plastic tubing insertion during experiments involving gas collection, delivery systems, or controlled chemical reactions. Made from durable, chemical‑resistant rubber, these bungs are ideal for repeated use in busy science classrooms.

Supplied in convenient packs of 10, these stoppers are perfect for class sets, group investigations, and everyday use in the school laboratory.

Key Features

• Durable rubber stopper with 1 pre‑drilled hole
• Bottom diameter: 21mm
• Top diameter: 24mm
• Length: 28mm
• Provides a secure, airtight seal for laboratory glassware
• Suitable for inserting plastic or glass tubing
• Chemical‑resistant, long‑lasting construction
• Supplied in packs of 10

Ideal for School Science Lessons

These 1‑hole rubber bungs are perfect for a variety of KS3, GCSE, and A‑Level practical investigations. They allow students to work safely and confidently when setting up experiments involving closed systems, gas flow, and controlled reactions.

• Creating gas delivery systems in chemistry practicals
• Sealing test tubes and flasks for closed‑system investigations
• Supporting experiments involving respiration, fermentation, or gas evolution
• Allowing secure tubing insertion for gas collection or transfer
• Ensuring leak‑free laboratory setups for accurate results

Reliable, durable, and classroom‑ready, these 21mm rubber stoppers are an essential consumable for every school science laboratory.