This pack of 10 solid rubber stoppers is made of superior-quality rubber in an orange color with a tapered shape. Each stopper measures 20mm in length with a 9mm base diameter and an 11.5mm top diameter, fitting bottles or flasks with a 10mm mouth opening. The stoppers are chemically resistant, suitable for use with acids, alkalis, and ammonia. They are stable at temperatures between -20°C and 70°C, easy to clean, and dishwasher safe. The durable rubber construction holds up to long-term use in laboratory environments.