Silicone O-ring requires no grease. Convenient side arms on cover and base. PTFE stopcock accpets 1/4" through 3/8" ID tubing. PTFE caps (two included) seal side arms when desiccator is used without vacuum. For room temperature use only; do not autoclave. Desiccator accepts desiccator plate 06521-00 (order separately). Do not autoclave. Do not expose polycarbonate to organic solvents or their vapors.