Used for microscale recrystallizing of small quantities of reaction product. Consists of a glass outer tube with a non-uniform grind to purposely allow leakage, and a PTFE inner plug. The PTFE inner plug fits both the 1.0ml and 2.0ml capacity outer tubes. Capacity listed is the volume of the tube below the ground seat. Sold as complete sets consisting of the glass outer and PTFE inner tubes, or as separate components.