Science teachers and lab folks, these EISCO neoprene stoppers are exactly what you need for your chemistry setups! This pack of 10 blue #4 size stoppers each have two 5mm holes perfect for inserting tubing or thermometers.
Made to ASTM standards, these stoppers measure 25mm long with a 20mm base diameter and 26mm top diameter. The neoprene rubber is seriously durable and chemical-resistant - it handles petroleum products, oils, fats, and most inorganic acids and bases without breaking down.
They can handle temperature extremes from -40°C all the way up to 130°C, so they're versatile for all kinds of experiments and demonstrations. EISCO manufactures these with quality control in mind, so you get consistent, reliable performance every time. Whether you're setting up distillation apparatus, gas collection, or any chemistry experiment requiring sealed connections, these stoppers have you covered. Perfect for educational labs, research settings, or anyone who needs reliable lab equipment!
Free 30-day returns 
Free 30-day returns
