Made of fine particle compressed cork, these rings are designed to support round bottom flasks, beakers, dishes and more. Cork is naturally elastic with very low thermal and electrical conductivity properties. Small cork stand has a diameter of 100mm and holds 250ml to 2000ml round bottom flasks. Large cork stand has a diameter of 120mm and holds 500ml to 3000mL round bottom flasks. Sold as a pack of 6.